Chuck Pagano had so many deep purple bruises on his thighs and torso that his wife actually thought he was tackling his players during the Colts’ training camp in 2012. He felt so tired that he might as well have been.

He pressed on, though, because that’s what coaches do in the first year of a job they’ve dreamed about their whole life.

Pagano would have continued marching on, too, if it weren’t for a quirk of the schedule. The Colts had complained all offseason about their early bye week, a Week 4 break that left them with 13 consecutive games to end the season.

It might have saved Pagano’s life. Had the bye come in Week 9, Pagano would have waited to be evaluated.

‘‘It ended up being a godsend,’’ Pagano said.

Before the Colts’ third game, he couldn’t take his own nagging fears anymore. He went to the training room and told the Colts’ doctors about his symptoms while players were preparing for a game they eventually would lose to the Jaguars on an 80-yard touchdown pass in the final minute.

They agreed to do his blood work in a few days, during the bye week.

Pagano had a light practice that Tuesday. After a team photo and a practice Wednesday, he went to the doctor. He sent his players home for the rest of the bye week.

When they returned the next Monday, they would hear the news: Their coach had acute promyelocytic leukemia.

Pagano, now the Bears’ defensive coordinator, has been in remission for more than six years. But to understand his mindset — his caffeinated, relentless mandate to make the most of every day — is to know his fight against blood cancer.

And vice versa.

‘‘We don’t take any days for granted,’’ said Pagano, 58, whom the Bears hired in January. ‘‘Every day that we get, we try to kick its ass, take full advantage of it. If you get another one, we’re going to do the same thing the next day.

“ ‘Live full, die empty’ is the motto now.’’

‘Set your jaw — and your spine’

Pagano made his living crafting game plans and adjustments for his players. Now, a few weeks before his 52nd birthday, he had to do the same for himself.

That Wednesday afternoon, Dr. Larry Cripe at Indiana University’s Simon Cancer Center told Pagano he thought he had APL. A bone-marrow biopsy proved it.

It had a high cure rate, but Pagano needed to start treatment immediately. He wasn’t allowed to go home to get an overnight bag because doctors were worried about his immune system.

‘‘Right then and there, it was: ‘OK, I’ve got the game plan. I know exactly what I have to do,’ ’’ he said. ‘‘You set your jaw — and your spine.

‘‘We talk to players about a game, one play at a time over 60 minutes. I used the same stuff on myself that I would have told my players based on how the game was going, at halftime, whatever: ‘You’re just going to have to take this thing one day at a time, trust these doctors.’ ’’

He and wife Tina, who accompanied him to the doctor, called their three daughters.

Pagano had made similar calls before. At 36, he had open-heart surgery. He had been on the receiving end of them, too. His sister Cathy died in a car accident at 22.

‘‘I hated cancer for everybody — my kids, my grandkids, my wife, my parents, my siblings,’’ Pagano said. ‘‘Losing a sibling, it doesn’t matter how long ago it was. It’s still something that you never get over. You learn to deal and cope with it, but, yeah, you hate it for everybody else.

‘‘That’s why you stay upbeat and you stay positive and keep letting them know that, ‘It’s going to be OK; it’s all good.’ ’’

He called Colts general manager Ryan Grigson, who passed word to owner Jim Irsay. Then Pagano went downstairs, was admitted to the hospital and had a PICC line stuck in his arm. Soon, it was pumping chemotherapy.

When Pagano got settled in his room, the nurses asked whether he wanted to be called Dwayne or Mr. Johnson. Tina had checked him in under an alias — one of the biggest movie stars on the planet.

He wouldn’t leave for another 26 days.

‘The price of love’

Cripe told the Colts’ players the next Monday. The world found out soon after.

Pagano’s phone became a chorus of pings. When Irsay found out Pagano didn’t have NFL Network in his hospital room, he paid for the channel to be piped into every room in the hospital. Every day, Colts staffers delivered a hard drive, filled with film from practice, that Pagano plugged into his computer.

When he had the energy, he texted and Facetimed with players and staff. They made long days seem shorter.

Pagano’s new Colts co-workers, hospital employees and average Indianapolis residents rallied around him. He was stunned. He had moved there only nine months earlier.

‘‘They didn’t know me or my wife or my family,’’ Pagano said. ‘‘We’d only been there a short time. But the way that they supported us and myself, wow.’’

When he returned to the sideline in Week 17 — three months after his diagnosis, the Colts were 10-5 under interim coach Bruce Arians — he was different. Having received letters of encouragement in the hospital, he now wrote them. Cancer patients and survivors attended games and chatted with him on the field.

Some of those lost their battles.

‘‘That’s what we call the price of love,’’ he said. ‘‘You build relationships, you have children, you love your family and you pray to God every day that nothing happens to them. . . .

‘‘That’s why you invest — because there’s really no other way to do it.’’

Pagano started the Chuckstrong Foundation in 2013 to raise money for cancer research. He held his seventh annual dinner in May in Indianapolis. The Bears bought a table, and general manager Ryan Pace and coach Matt Nagy attended. Irsay, who had fired Pagano after the 2017 season, donated $1 million. Pagano has raised $7.3 million in seven years.

‘‘It was really unprecedented,’’ Pagano said. “In the National Football League, where everything is so secretive — nobody wants to share anything — for two organizations to come together . . . it was unbelievable.”

He has booked the 2020 fundraiser in Indianapolis, too. In a way, it’s still home. So the Bears’ return to Indianapolis for a preseason game Saturday is special.

‘‘You go through what he went through those five or six years there,’’ Nagy said. ‘‘Not just on the football field [and] the relationships you build, but obviously with his research that he’s done there and so many positive relationships. To this day, the friendships that he’s had with so many people in that city, I think it’s a feel-good story that more people need to know about.’’

Pagano calls the way he was treated, then and now, ‘‘Hoosier hospitality.’’

‘‘Until you live it, like I had an opportunity to live it, you can’t appreciate it like I appreciate it,’’ he said.

‘We’ve got a team again’

Football isn’t war. It’s not life and death. Just ask the man in remission.

‘‘When we cross the white lines, we’re pretty much guaranteed . . . you’re allowed to go home with your family,’’ he said. ‘‘It gave me great perspective on things. You’re grateful for every opportunity you get.’’

And grateful, in retrospect, to step away.

He took a gap year in 2018 after the Colts fired him, working a few days a week as a consultant for NFL officials to help them understand how coaches viewed their calls.

He practiced what he called the three R’s — he reset, recharged and reflected. He saw his nephews play football at Michigan and Boise State and even tailgated beforehand. He went to the Masters. He danced at his daughter’s wedding.

He became a Peloton addict, riding up to four times per day. That habit stuck, even after he was hired by the Bears.

‘‘He’s a maniac,’’ Nagy said. ‘‘That’s the first thing he does at, like, 4:30 in the morning.’’

Pagano says now that every coach should be so lucky to have a year to catch his breath. But he missed football. A part of him felt empty without it. Last year, he would take clean clothes to the dry cleaner just to have something to do.

‘‘And then it would be noon,’’ he said. ‘‘It’s only noon? And then you try and figure out what you are going to do with the rest of the day.’’

He never had missed a football season and is thrilled he doesn’t have to again.

‘‘It’s what I do; it’s what I love to do,’’ he said. “Thirty-three straight years, man. And then you don’t have it, you don’t have a team? My family, my wife, my kids don’t have anybody to root for.

‘‘Now we’ve got a team again. . . . I’m truly blessed to be here.’’

He walked into, by his own admission, the ‘‘very best situation.’’ No team in the NFL allowed fewer points than the Bears’ 17.7 last season. Only two gave up fewer yards than the Bears’ 299.7. The Bears led the league in takeaways and interceptions under former coordinator Vic Fangio, who parlayed the dominant performance into the Broncos’ head-coaching job.

Pagano interviewed for that job, too. It would have been a homecoming because he grew up in nearby Boulder, Colorado. Once he landed in Chicago, though, he said he put aside the dream of being a head coach again.

‘‘There’s a lot of things that coach Nagy would tell you sitting in that chair now for a year,’’ he said. ‘‘And I sat in it for six years. There were many times when I was sitting in that chair, I said: ‘Boy, I wish I was a defensive coordinator again.’ ‘Man, do I wish I was a secondary coach.’ It wasn’t nothing to do with coaching; it wasn’t nothing to do with the football part of it. It was just some of the other stuff that comes with it. . . .

‘‘I’ve done it. I’m motivated to just help coach Nagy be successful, help this organization to be successful, help these kids grow and develop. My motivation is to be the best that I can be for this organization.’’

‘I feel very lucky’

Pagano speaks like a preacher. He has sayings — ‘‘So what? Now what?’’ and ‘‘I’m better, not bitter,’’ among dozens of others. Cornerback Prince Amukamara’s favorite is ‘‘skin like an armadillo,’’ Pagano’s demand that his players not take criticism personally.

Amukamara laughed when asked whether Fangio, whom Bears players absolutely adored for his no-nonsense approach, even knew what an armadillo was.

The two coordinators couldn’t have more different personalities. The Bears have to wait until the regular season to see whether that’s the case with their on-field play-calls. Last season, Fangio would call a certain coverage — say, cover-2 — and, if it worked, Amukamara knew he’d call it on the next play. Now, he’s not sure.

‘‘You can tell that [Pagano] has been a head coach before, just how he demands respect in the room,’’ Amukamara said. ‘‘When he walks into the room, you can tell that he has that presence about him. He’s already earned our respect.

‘‘He always likes to be vulnerable and transparent and share his experience about his heart surgery and his cancer and all that. We can tell that he’s a strong-willed individual. He kind of gives us the tools to have that mindset.’’

Inside linebacker Danny Trevathan said Pagano ‘‘appreciates every day, and that’s big to me.’’ Outside linebacker Khalil Mack, who will be Pagano’s shiniest new toy, gave him the highest compliment.

‘‘You’re talking about one of the best people that I’ve had the chance to work with,’’ he said. ‘‘And that’s what I’m looking forward to this year.’’

The feeling is mutual.

‘‘They’re a bunch of gym rats,’’ Pagano said. ‘‘You know the talent level — everybody can see the talent level — but their passion for the game and the city and the organization . . . being a Bear and playing for that team and representing that decal on the side of the helmet, it’s mind-boggling. It’s off the charts.’’

Repeating the Bears’ defensive dominance is as tough a task as any coordinator in the NFL will face this season. In the last six seasons, six teams have led the NFL in takeaways. Teams simply don’t repeat.

‘‘Every year is different,’’ Pagano said. ‘‘You’ve got to stay healthy, and the ball’s gotta bounce your way. But it’s an unbelievable group. The assistants are phenomenal. I feel very lucky.’’

Pagano is hopeful. As always.

‘‘He’s just such a positive human being,’’ Nagy said. ‘‘He’s about being optimistic. He’s about being real. He’s about being honest. He’s about treating people the right way.

‘‘When you do that and it’s natural and it’s not fabricated, it’s not made up, it’s not fake, the trust and the belief that your players have with you as a coach happens so much quicker.

‘‘He has a challenge. We have a challenge on defense. But there’s nobody in this league that wants to attack something as aggressive as coach Chuck does.”