MANKATO, Minn. -- Of the many pictures that line the walls of the Minnesota Vikings' practice facility in Eden Prairie, some will not be there long enough to be dusted.

Players return each spring to a new look. Photos of past Vikings Pro Bowlers were added to the team's makeshift meeting room this year, and pictures of fresh mission statements sit along the path from the locker room, through the weight room and into the Vikings' indoor practice facility.

Mike Zimmer has carefully curated the look of his team's working environment -- an odd task, considering the coach's nonplussed reaction to designers who dared approach him during the middle of a football season to ask what color wood he wanted in the locker room at U.S. Bank Stadium. But there is a message embedded in the shifting photos on those walls: Change, in this line of work, is a constant. You can embrace it, adapt to its rhythms and even use it to your advantage, or you can let it knock you on your ass.

Vikings coach Mike Zimmer has this picture of his dad, Bill, hanging in his office, reminding him of the man who first influenced his coaching style. Courtesy\Zimmer family

The photo just inside the door of Zimmer's office is of a man who might be the patron saint of this philosophy for the Vikings. He appears timeless, kneeling in a white shirt and white pants in a field in front of a shed, a football in his hands and a coach's whistle hanging from his neck. His neatly cropped hair and dimpled grin evoke Rockwell and Rockne, and he has the backstory to match: two years in the United States Army, a season in the NFL with the San Francisco 49ers and 35 years as a high school physical education teacher who became an Illinois high school hall of fame football and wrestling coach. Don't for a second think, though, that Bill Zimmer was static.

You want to know how Mike Zimmer has become one of the NFL's hottest new head coaches at age 60, with an 18-14 record and an NFC North title in two years at a temporary stadium (and one without his star player)? Want to know how this self-styled fixer has led six top-10 defenses over 16 seasons in four cities, shifting from his preferred 4-3 to a 3-4 in Dallas and helping the Vikings make a year-over-year jump of 21 spots in scoring defense during his first season? That success does not come without the ability to change and adapt. Go back before Zimmer's tenure under Bill Parcells, to the fields of suburban Chicago, where his football education began at the side of a man who started each season in the shifting sands of prep football, searching for an answer to the question, "How can I win with this team?"

Bill Zimmer's teams ran the run-and-shoot while it was still just a novelty. He was among Illinois' first coaches to shift from the sideline to the press box, so he had a better view of the entire field. He'd drive to coaches' clinics at gilded college programs in Alabama or Nebraska, returning with reams of information on things he could use in his own program. His last playoff team in Illinois, after years of "Air Zimmer" offenses, ran the wishbone because that's what its players could do well. Fondness for, or comfort in, the way things used to be done was no excuse not to evolve.

His father's annual question was programmed into Mike Zimmer's cell phone during his first training camp with the Vikings, popping up each morning as a kind of north star for the new head coach. However flexible and innovative his father was, though, Mike Zimmer also admired things about him that would not change.

"My dad was a guy who wasn't afraid of anything. Ever," Mike Zimmer said. "[He was always] driving you, pushing you further."

That came through hard lessons learned on the wrestling mats of Lockport Township High School. As a sixth-grader, Mike would walk nearly a mile from Kelvin Grove Elementary School to the high school to grapple with his dad, and high school athletes, after he was cut from the basketball team. It came from a high school football coach who required his son to address him as "Coach" on the field, who once punched him in the chest after he threw an interception, whose practice-field spats with his son would bleed over into silent rifts at the dinner table. Those trials came during "my rebellion years," Mike Zimmer joked, and though there might have been days when his father's toughness felt like meanness, they've helped form the alloy of resolve and perfectionism that surrounds his work as a coach now.

They've also steeled Zimmer in his toughest moments, turning the proving grounds of a football field into a refuge when change levied its harshest wounds. Three days after his wife, Vikki, died unexpectedly in 2009, Zimmer was in his familiar spot as the Cincinnati Bengals' defensive coordinator, earning a game ball from head coach Marvin Lewis following a 17-14 win over the Baltimore Ravens. And a year ago, the day after Bill Zimmer died at 84 in Naples, Florida, Mike Zimmer was back on a Mankato practice field, as his daughters Marki and Corri visited Minnesota State to console Mike and his son Adam, the Vikings' linebackers coach.

The charitable foundation Mike and Corri Zimmer launched this spring is a tribute to his late wife, a doting mom who baked cookies for Mike to bring to practice and reminded him not to be so hard on his players. It will provide scholarships to Minnesota students in future years, but one of its first acts this spring was to go back to Lockport to award a $10,000 scholarship in Bill Zimmer's name with memorial donations from his funeral.

"I think he feels very blessed to have a father like he had," said Vikings general manager Rick Spielman, himself a coach's son. "I think [it's] similar to my situation. They taught us not only a lot about football, but about the important things in life -- from treating people the right way to being a leader and a teacher."

Sports was all he ever wanted to do

The son of a farmer, Bill Zimmer played guard and linebacker at Harrisburg High School in southeastern Illinois before earning a scholarship to Bradley University. His two years in the military and his season with the 49ers came before he returned to Bradley as an assistant football and golf coach, and in 1959, he became the football and wrestling coach at Lockport Township, teaching drivers education in addition to PE classes.

Zimmer said he developed his work ethic and toughness from his father, but he learned an 'awful lot' of football from Bill Parcells. Benny Sieu/USA TODAY Sports

The Zimmers' house in Lockport abutted the high school practice fields, and from an early age, Bill Zimmer's oldest son was a fixture there. Mike took an interest in farming and hunting, from his grandparents, but his mother knew where he was headed.

"He was always a quiet kid," Ann Zimmer said. "He wasn't real demonstrative at home -- although he was the boss. He had a brother and a sister, but he would always come in and take over, because he was the big brother. I didn't see him doing anything but sports. That's all he ever wanted to do."

Mike Zimmer would tag along to football practice, where his dad's search for perfection occasionally stretched longer than the school bus was willing to wait. "He'd say, 'One more play, one more play,' about 100 times, and the kids would keep doing it," Mike Zimmer said. "And then, if some of the kids would miss the bus, he'd drive them across town, wherever they had to go."

If those practices taught Mike about discipline, wrestling hard-wired it into his psyche.

"That was the hardest thing [I did]," he said. "It was just tough. You had to be physical. You cut weight, you're in there and you're just grinding. It's just you and [your opponent]. We used to wrestle together a lot, me and [my dad] -- which was legal, because we were in the mat room."

Father and son whiled away long days together on the fields and mats of Lockport. By the time Mike was 14, his dad sneaked him behind the wheel for early drivers training. Once, when Bill Zimmer needed to settle a score, he brought his son with him.

"[My dad] told a really funny [story] at [my grandpa's] funeral, that my grandma didn't even know about," Corri Zimmer said. "One time, [my grandpa] had a problem with somebody, and my dad was probably around 15 or something. He was like, 'Hey, Mike, come with me.' He took my dad along for backup because he was going to beat this guy up. My grandma was sitting [at the funeral], and she was like, 'What?'"

By the time Mike left for Illinois State University in 1974, he'd already been imbued with the hardiness of a father who rose early each morning in search of ways to be a better coach. But he was convinced he was going to be a professional football player, and had no thoughts of following his dad's footsteps into coaching until a neck operation ended his playing days. He took a graduate assistant job at Illinois State, beginning his path to what became the Zimmer family business.

Kindred spirits

There would be nothing handed to Mike Zimmer as a coach, and to this day, he's proud of the fact that both he and Adam Zimmer -- who worked for two teams as an assistant linebackers coach before joining his father -- had to prove their mettle at a number of different stops. Mike Zimmer worked for nearly two decades as a college coach, becoming Washington State's defensive coordinator in 1989, before the Dallas Cowboys gave him his first NFL coaching job in 1994. He stayed there for 13 seasons, spending the last four as the Cowboys' defensive coordinator under Parcells, who took a liking to Zimmer's preparedness and quickly realized where it came from.

"We're all products of our upbringing in this business," Parcells said. "When we transitioned defensively in Dallas [to a 3-4 scheme after I was hired], it was something he wasn't familiar with at the time. It was a new scheme for him, so he learned it and coached it. This guy is a football coach. He's not interested in any ancillary issues, he's not caught up in anything but coaching football. He's sleeping and eating it. That's what he does. I like that. That's the way I was brought up."

"I think he feels very blessed to have a father like he had. I think [it's] similar to my situation. They taught us not only a lot about football, but about the important things in life -- from treating people the right way to being a leader and a teacher." Vikings GM Rick Spielman, who gave Mike Zimmer his first head-coaching job.

Who influenced Zimmer more: his dad or Parcells?

"I think my dad instilled the work ethic, how to be and the toughness part of things -- the competition and all that," Mike Zimmer said. "But I think maybe as a coach, Parcells. I learned an awful lot from him."

Zimmer had been a defensive coordinator for seven seasons and led three top-10 units by the time Parcells retired from the Cowboys in 2007, yet his head-coaching interviews always ended without a job offer. In those years, as frustration turned to dejection, phone calls to his father were a frequent outlet for Zimmer. And it wasn't until 2014 that another coach's son decided to take a chance on Zimmer as a first-time head coach, after they'd clicked over discussions on their shared backgrounds.

Spielman and Zimmer talked for more than 15 hours over the course of two interviews. Their first meeting at a hotel didn't even include dinner -- "We had some chips and pretzels," Spielman said. "He's not a real fancy guy, anyway" -- but by the end of it, they knew the match was right.

"It's just like when you meet the right person, or who you think is the right person. You can sit there and talk for hours on philosophy, on ball, how you grew up, your beliefs," said Spielman, who played at Ohio's famous Massillon High School when his father, Sonny, was an assistant there. "I don't want to call it the old-school mentality, but I think we had similar philosophies that way. One thing I think my dad taught me and my brother [Chris, a four-time Pro-Bowl linebacker] the most was, there may be more talented people out there, but the one thing you always control is your work ethic and your approach."

Mike Zimmer (left) was the quarterback for his father's Lockport (Ill.) Township football team. Courtesy\Zimmer family

Spielman was leading a coaching search for his first time as a general manager. He placed his first bet on Zimmer, recommending the Bengals defensive coordinator to Vikings ownership, and the team hired him on Jan. 15, 2014. Two years later, Zimmer has a contract extension that reportedly adds two years to his original deal, which ran through 2017. The Vikings have the power structure they'd sought since the Wilf family bought the team in 2005, between two coach's sons who both say they've had few disagreements over the course of their time together. Zimmer says he has no desire to be a general manager, but Spielman has said what an asset the coach is during the annual scouting process -- in part because of his open-minded approach that he learned from his father.

"One of Zim's strengths is the ability to identify what he sees as positives and weaknesses in a player, and how he's going to utilize the positives to fit what we do, but also to adjust what we do," Spielman said. "One of the big examples of that was in our first draft together with Anthony Barr, who people didn't think was going to be a fit here. We've been together for three drafts now; we have a pretty good understanding of what he's looking for, and he has a very good understanding of our process. Communication is the whole key."

'A very proud father'

The Vikings' hiring of Zimmer triggered applause from various corners of the league, as players who'd toiled for the coach praised the Vikings for recognizing what others had missed. They reverberated all the way to Naples, Florida, where Ann Zimmer believes the chance to see his son become an NFL head coach did no less than extend Bill Zimmer's life.

Shortly after Mike Zimmer got the Vikings job, Bill Zimmer became ill from an infection he'd developed after an outpatient surgery to remove a melanoma on his leg.

"We get in the hospital room, and he was very ill," Ann Zimmer said. "They kept saying to me, 'What about his condition?' I said, 'Don't ask me -- ask him.' He said, 'I don't want to die.' He wanted to get to Minnesota to see Mike. That was his goal for keeping him alive the last two years [of his life]. He was a very proud father."

The Zimmers actually saw two games during their son's first year as head coach. They came to Minnesota for the Vikings' game against Detroit in October 2014 and got the chance to attend the team's loss to the Dolphins in Miami four days before Christmas, when the activities director at their golf course community sent out a notice about a group outing.

"Every year, she'd get [tickets for a game]. It was usually like New England or somebody," Ann Zimmer said. "I went in to her and I said, 'Did you have very many people sign up?' She said, 'No, not so many.' I said, 'Do you know who the father of the head coach is? It's Bill Zimmer.' She put that in [the notice], and after that, the bus filled up. We had 50 people that got to go to that game. I called Mike and said, 'How about a box lunch for these people?' Of course, he complained, but he did it. He told somebody, 'I don't know how my mom roped me into that,' but everybody on the bus thought he was Mr. Wonderful."

Bill Zimmer and his wife, Ann, were in attendance for two of Mike's games as an NFL head coach, and the pride in Bill was immense. Courtesy/Zimmer family

The Zimmers ordered DirecTV so they could watch every Vikings game from their house in Florida; another couple would stop by every Sunday, and the four would split a pizza. While Ann Zimmer would scream at the TV, Bill would quietly take it all in, a wizened coach processing what was in front of him. And after each game, he'd call his son to break things down.

"There were a lot of times throughout my coaching that he'd call, and know I'd be upset," Mike Zimmer said. "He'd say, 'Hey, you've got next week,' and that kind of stuff."

The calls from Florida were of a different tone last August. Mike and Adam Zimmer got word that Bill's health had taken a turn for the worse, and departed Mankato for Naples. When they arrived, they saw a hospital room decked out in Vikings gear. The old proprietor of the family business perked up, and he wanted to go to work.

The final, sweet moment Mike Zimmer had with his dad came on that trip, when he broke out his tablet to watch film of the practice he'd missed in Minnesota.

"He gave it to my grandpa and said, 'You want to look at it?'" Adam Zimmer said. "He hadn't moved his hands since we'd been there, and he picked up the iPad and just watched it, like an old coach. He couldn't really talk at the time, but you could tell he was mentally engaged."

Just over a week later, Bill Zimmer passed away. His funeral was put on hold until after the Vikings' second preseason game against the Tampa Bay Buccaneers, and when he flew to Florida, Mike Zimmer finally let it all out.

"At the funeral, he was crying almost the whole time," Corri Zimmer said. "You could definitely tell he was my dad's hero, and he looked up to him so much. He wouldn't be here today without him."

The Zimmers asked for donations to Mike's new foundation in lieu of flowers, and they got more than $8,000. They made plans to create a scholarship in Bill's name for a football player at Lockport, and when the applications came in this spring, Corri Zimmer called her brother and asked him to read the essays with no background information. Adam Zimmer said he had a clear favorite; it was the same one Corri and Mike had picked.

The applicant was Gabriel Lammers, a linebacker whose mother and grandmother Bill Zimmer had taught to drive. Before Lammers' junior year, he found out his older brother Zack -- a receiver on Lockport's 2002 and 2003 state championship teams -- had accidentally fallen to his death from the balcony of his Chicago condo. The grief-stricken younger brother thought about quitting football, but decided to stay and switch from his No. 44 to his brother's old No. 11.

"We're all products of our upbringing in this business. ... This guy is a football coach. He's not interested in any ancillary issues, he's not caught up in anything but coaching football. He's sleeping and eating it. That's what he does. I like that. That's the way I was brought up." Bill Parcells on Mike Zimmer

"I remembered all the conversations I had with Zack about what football meant to us," Lammers wrote. "We loved everything about it -- the physical aspect, the competitiveness and the camaraderie developed between teammates. I wanted to make him proud, so I dedicated my season to Zack. ... Above all, my teammates and coaches were supportive, providing me with a place where I felt safe and normal, when all around my world was falling apart."

Lammers had found the same sanctuary the Zimmers flocked to when Vikki died, and when Bill passed away. And in a way, Bill Zimmer's final act was one more gift to the school he loved so much.

"He became a lot more sentimental in his old age. He was not very sentimental when he was younger," Mike Zimmer said. "Now, I think he would think it was pretty cool. He had such a huge influence on that school, because he basically started the program, ran the program for [35] years."

A generation later, Corri Zimmer sees her father doing the same thing.

"He's super soft, especially with me and my sister," she said. "He does whatever he can to help us, and go out of his way to make us happy. It was definitely more after my mom passed away; he had to kind of take on the role of the mother and the father. My sister and I would always go get our nails done with my mom, and he would start going with us. It's something that would never have happened before she passed away. After she passed away, he would bring his phone out to practice [in Cincinnati], and we could hear hitting in the background. We're like, 'Did you just answer during practice?' He's always been a good dad, but he had to really step it up, and he has."

Mike Zimmer's foundation will award its future scholarships to students in Minnesota, and its early fundraising efforts were kick-started by the "In Zim We Trust" T-shirts dotting the stands at training camp.

"I'll go, 'Think about how many grown men want to wear your face on their chest,'" Corri Zimmer said. "He just laughs about it. He's definitely very modest about it, but I know he sees it, and I know he appreciates it."

He has become wildly popular in Minnesota, but Mike Zimmer will not boast about it, instead remaining wary of how quickly perception can change with a losing season or two. While Vikings fans send expectations skyward for a season they hope can end with a Super Bowl, the team's coach stays grounded the way his dad taught him to do it: by rising early, constantly in search of the answer to the question, "How can I win with this team?"

On Thursday, the one-year anniversary of his father's death, Mike Zimmer will be back in Cincinnati, in the city where he lost Vikki, surrounded on the Bengals' practice fields by his new players and many of his old ones. Adam will be there, too, coaching the Vikings' linebackers during their joint practice with the Bengals, instructed not to call his father "Dad" on the practice field, aware of the unremitting standards he must meet.

"He tells me, 'I'm going to be tougher on you, because I want you to be better than me,'" Adam Zimmer said.

Some things change, and some things do not. The family business rolls on.

"I think," Corri Zimmer said, "that the Zimmers are all about tough love."