LONDON -- It all began 16 years ago as a bridge, a way for Bob Bowman to make a few dollars and kill some time before moving on to the next stage of his life. Maybe he would work with horses. Maybe he would go to veterinary school. But he certainly wasn't going to be a swimming coach. Not for more than the next year or two.

Yet more than a decade and a half later, here is Bowman now, arguably the most famous water maestro in the world, the man who has pulled the strings and pushed the buttons for the greatest swimmer of all time.

Sometime around 10:25 a.m. here on Saturday, Michael Phelps will dive into the water for a preliminary heat of the 400-meter individual medley and begin the last swimming meet of his decorated career. Standing beside the pool analyzing every stroke and kick will be Bowman, who has been by Phelps' side for this entire journey.

Their relationship hasn't been easy. There have been fights and arguments, and enough drama to fill an afternoon soap opera; but at the same time, there has been respect, admiration and unprecedented success.

"We've figured each other out and that's why it's so complicated," Bowman, 46, said. "We know everything there is to know about each other and we both know how to push those buttons whenever we want to."

In 16 years, Bowman has watched a hyper, awkward 11-year-old with a freakish body grow into a 16-time Olympic medalist, a global brand and one of the most recognizable athletes in the world. In this, Phelps' last Games, the two have found an ability to relax, unwind and enjoy themselves. Phelps has become more of a team leader, while Bowman has transformed from a driven, demanding, my-way-or-the-highway drill sergeant into a man who realizes there is more to life than the perfect split in the 400 IM.

In a little more than a week, one of the greatest marriages in American sports history will come to a close. But before the last walk off the deck, Bowman sat down with ESPN.com for an exclusive interview to discuss the evolution of his relationship with Phelps, why he worried Phelps wasn't going to swim in London and what life will look like on Aug. 4 when coaching the swimmer is longer Bowman's No. 1 priority.

It's the middle of Thursday afternoon, less than 48 hours before Phelps' first competition in London, and he and Bowman sit atop an elevated podium in the Main Press Centre. The questions are coming from left and right, not only American journalists, but more from Australia, Brazil, England and France, among others. There isn't an empty seat in the room and not much free space on the floor.

Phelps and Bowman even joke with the media, pulling out cameras after climbing onto the dais to take a quick snapshot of the scene below.

"I want to take a photo of all you guys," Phelps says.

A few minutes later, a reporter asks Phelps what exactly makes him a superstar. Before he can answer, Bowman interjects.

"It's all coaching," he says with a grin.

Phelps, seated to Bowman's left, laughs. So hard, in fact, he nearly falls back off his chair. And then he laughs some more. There's a moment of silence before Bowman then speaks again.

"Next question," he jokes.

Early Friday morning, Bowman tweeted a picture of him and Phelps standing on the pool deck after their last practice, arms around each other with both of them grinning from ear to ear. Yes, it's all laughs and smiles right now. This is the emotional farewell tour. It's hard not to enjoy it. But getting to this point hasn't been easy.

While most Americans will turn on their televisions this week and see Phelps make swimming on the biggest stage look oh-so-easy, the path back to the Olympics has been a treacherous one, with Bowman calling it a "miracle" that they are even here.

After his record eight gold medals in the 2008 Beijing Olympics, Phelps drifted away from the sport that had given him so much. Part of it was a lack of motivation after accomplishing something that had never been done before. Part of it was exploring life away from the pool, where he had spent seemingly every minute of his teens and 20s. And part of it was simply boredom.

"Even when he came to practice, he was so disengaged," Bowman said. "There was no light on."

Bowman knew the amount of work it took to be an Olympic champion; Phelps didn't care. He wanted to play golf, not swim.

"Honestly, the first 12 years were easy," Bowman said. "I had a plan, laid it out, he did it and things happened. This time I had a plan, laid it out there and he didn't do a lot of it, so I had to change the plan, which I don't like to do.

"I had to decide, was I going to let go of being so hardheaded in terms of 'I want it this way, this is the perfect way, this is how we should do it,' to 'This is where he is right now. Let's meet him there and take a step forward every day.'"

Bowman looked on as Ryan Lochte stole the show at the 2010 Pan Pacific Championships, winning four individual gold medals, while Phelps won two and appeared unfazed.

"He didn't get it yet," Bowman said.

In early 2011, Phelps hadn't trained in nearly two months when Bowman took him to altitude before a Grand Prix meet in Indianapolis and tapered him.

"I wanted to see what we had," Bowman said.

What Phelps had calmed Bowman's nerves. Phelps won the 100 and 200 butterfly, swimming the fastest time in the world that year in both events.

"That gave him a little confidence that he could do this," Bowman said.

That's when training intensely for London began.

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Letting go

Like many successful coaches, Bowman is an admitted control freak. He doesn't like to leave things to chance. And by letting go of his usual routine, Bowman thought he was risking Phelps leaving, or, perhaps worse, Phelps returning but not as the swimmer the world had come to know.

Bowman attended Florida State as a musical composition major, but earned his bachelor's degree in child psychology. He had used those lessons for more than a decade to push Phelps to places he never dreamed possible. But what if he couldn't reach Phelps this time? What would it say about Bowman's legacy and abilities as a coach and motivator if he led the greatest swimmer of all time to a dud of a performance?

"I started thinking, 'What happens if this goes bad?'" he said. "'What are you going to do if we get to the end, this doesn't work out and, well, that's it?'"

For years, Bowman had tied his happiness to Phelps' swim times. His self-esteem, his reputation, they were all tied to what Phelps did in the water. A great practice meant a great day; a miserable practice meant a miserable day. At big meets, Bowman's emotions would yo-yo up and down even more violently. "Everything he did, I carried with me 24/7," Bowman said.

He couldn't keep this up. He had to change. He had to find peace. The bachelor sacrificed so much -- a personal life, a family, holidays, a love for horses and travel -- to stand on a pool deck every day and bark instructions to Phelps and his other swimmers. But he had to change, and he made a simple conscious decision to do just that.

"I started trying to just separate the swimming and what we were doing there from me and my life and Michael and my life and what we were going to do beyond," he said. "One of the things I came to realize is that my happiness is not dependent on his swimming times."

When he shared the news, Phelps was shocked. At a 2011 Grand Prix event in Austin, Phelps swam the 400 IM in 4:15. While Phelps wasn't particularly pleased with the time, it didn't bother Bowman. Later that night, Phelps texted his coach with a question.

Are you upset?

"No," Bowman responded. "I'm enjoying a glass of wine from room service."

Why not?

"Because," Bowman said, "the most important thing I've learned in the last four years is that my happiness is not dependent on your swimming times."

Bowman jokes life could have been a lot easier if he had found this place of peace sooner, but he's glad he found it at all. By letting go, Phelps has come back. And Bowman thinks his ability to relax and give the adult Phelps more space is one of the reasons they both find themselves back here in London eyeing gold in seven events.

"As soon as I starting approaching it, like, 'Here's practice, let's get done what we can get done, it might not be perfect, but let's do what we can do,' things got really good and he started giving a lot more effort," Bowman said. "Then it all fell into line."

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Just like flipping a switch

As he walked through the gargantuan shopping mall attached to Olympic Park this week, Bowman breezed with an air of confidence. It was the first time he had been outside of the park and even then he was only here for an interview.

He mentioned the competition pool appears fast and bragged that training has been going spectacularly well. The man has never been one to mince words. When Phelps has struggled, Bowman has been the first to say so. When Phelps has soared, he has done the same.

And this week, it seems, Bowman is predicting an impressive finish.

"He's right there," Bowman said. "I don't have any doubts he's going to be right there. I can't control what other people do, but I think he's going to swim really, really well. Whatever he's got, he's going to give it."

Three and a half weeks ago at Olympic trials in Omaha, Neb., Phelps beat rival Lochte in three of the four events in which they both entered. But his combined margin of victory was a mere three-tenths of a second. Afterward, Bowman suggested Phelps was at about "80 percent" of where he thought the swimmer would be in London. But now, based on how far he believes Phelps has come since trials, he thinks that number was low.

"He's swimming now like he has swam before some of his really good meets," Bowman said.

Think about that. At less than 80 percent of his ability, Phelps beat the best American swimmers in every race except one. That race, the 400 IM, is the first event on his docket Saturday.

Since Beijing, Bowman had worried that Phelps, like many great athletes, believed he could just flip a switch, throw himself into training and instantly regain his world-class form.

But, in the end, it seems Phelps was right. When he's focused, his talent, ability and work ethic all allowed him to do just that.

"He was right," Bowman conceded. "But it still took eight months for him to turn it on, and it wasn't like we destroyed people at Olympic trials."

Now when he tries to figure out exactly what to expect out of Phelps at a major meet, Bowman spends less time worrying about strokes and splits and more time paying close attention to Phelps' mood. Is he happy? Relaxed? Enjoying himself? Bowman said when Phelps is, good things are about to happen, and that's the way things have been this week.

For example, Bowman was concerned that Phelps may have grown agitated after spending a few days in his athletes' village bedroom; the rooms do not have air conditioning, and temperatures climbed into the upper 80s for much of the week. But when Bowman asked Phelps on Wednesday how his room was, Phelps insisted it was fine.

"When he's in that mode, nothing bothers him," Bowman said. "When he isn't, he'll just complain about everything, and that's wasted energy. I've tried to tell him not to waste any energy complaining about everything. Put it in your swimming and let's see how it goes. This week, he seems to be in a great place."

The next chapter

For 16 years, the routine has been the same. Sure, Bowman has tried to mix things up, tweaking this or twisting that in hopes of keeping Phelps engaged. But the reality is, training for the Olympics is physically and mentally exhausting. It's repetitive, and that can make it boring at times.

One of the pillars of Phelps' training program has been a series of butterfly swims he has done one week before a major meet. It's simple, really: three 100-meter butterflies at full speed.

"It started when he was young," Bowman said. "It gives us a lot of information about where he is and how he's doing. It's something we know that when we do it, we don't ever want it to go badly."

Last Saturday in Vichy, France, where the U.S. swimming team was training before heading to London, there was Bowman, telling Phelps to do his three descending butterflies for the last time.

"It went really well," Bowman said. "And then afterward it was like, 'Wow. That's the last time we'll do that.' I got a bit emotional."

No matter what happens this week, Bowman believes Phelps will go down as the greatest Olympian, if not one of the greatest athletes, of all time. And you can believe this is the end. Phelps has repeatedly insisted there isn't going to be some grand comeback for Rio 2016, and nearly everyone around him believes it. If Phelps wins three medals this week, he will pass Russian gymnast Larisa Latynina for the most individual medals in Olympic history. There's nothing left to prove.

"Michael wants to be remembered as the best ever," Bowman said. "And I want to be remembered as someone who helped get him there."

After London, Bowman said he plans on taking a year off and traveling the world, visiting places like Tuscany. He also wants to have more of a normal life, complete with holiday barbecues and vacations, to try to make up for so many of the things he's missed along this improbable journey.

"Whether I look back and say it was good or bad, things worked out pretty well for me," Bowman said. "I'm happy with where I am and what I do, but I want to have a Memorial Day. I want to have a spring break. This year I'm doing the whole spring. I'm taking them all. Consecutively."

Will his respite be just a year, or is this is the end for Bowman as well?

"We'll see where it goes," he said. "I have some doubts that I can actually be unscheduled for maybe even a whole year. We'll see."

In the end, it's been a heck of a ride. The man who showed up in Baltimore hoping to kill a few years while saving money for veterinary school has become one of the most respected and recognizable Olympic coaches in history. Like his star pupil, Bowman has grown and evolved over time. He's learned as much about himself as he has about Phelps.

And though Phelps won't be competing any longer, his relationship with his coach is hardly going to end. Bowman and Phelps are sure to have some time apart, but they will work together as part of Phelps' foundation and IM program that teaches children how to swim and encourages a healthy, active lifestyle.

"He's not going to get rid of me too easy," Bowman said.