‘I’m having fun again,’ Michael Phelps says, heading into his final week of the Olympics

Reporting from Rio de Janeiro —  He has 23 Olympic medals and a line of swim gear emblazoned with his initials. He endorses razors and watches and beef jerky — even a mobile phone application bears his name. He holds three individual world records, is a regular on morning talk shows, and an anticipatory buzz ripples through the Olympic Aquatics Stadium each time the world’s most famous swimmer steps onto the starting block in what is likely the final week of his career.

But the most profound change in the life Michael Phelps can be seen in a recent photograph. Phelps is dozing while his infant son, Boomer, born in May, does the same on his chest. Both of their mouths are wide open. The peace that collecting more medals than any other Olympian in history couldn’t produce, the peace that eluded Phelps for so many years, finally seems present.

“I’m having fun again,” Phelps said. “I’m enjoying what I’m doing again. I think I’m at the point that, whatever’s left, I’ll be able to turn the page and say I was able to finish the way I wanted to. And to me, that’s all that matters.”

Phelps carried the U.S. flag in the Opening Ceremony last week, an honor bestowed on him by his Olympic teammates, some of whom grew up asking for his autograph or hanging his picture on their bedroom wall.

Phelps has already helped the U.S. win a gold medal in the 400-meter freestyle relay in what he says will be his fifth and final Olympics. The blazing time in his 100-meter leg could portend similar success in his three individual events, starting with the 200-meter butterfly final Tuesday.

“Michael usually works this way,” said Bob Bowman, who has coached Phelps for two decades. “When one thing is really good, everything is pretty good. He doesn’t usually work in parts. So I feel pretty good now.”

Each race is more emotional, more meaningful for the 31-year-old because of the finality. There won’t be another opportunity in four years. This is it. But his perspective now extends beyond swimming.

Michael Phelps encourages teammate Nathan Adrian to finish strong and seal the gold medal in the 400-meter freestyle relay on Sunday.

(Robert Gauthier / Los Angeles Times )

“He’s just so mellowed out,” said Jon Urbanchek, his close friend and legendary coach who served as an assistant for seven U.S. Olympic swimming teams. “He’s loving, caring. He’s going to be a great father. Swimming is not the only thing in his life. This child is. It doesn’t matter that he has a [bad] workout. It doesn’t matter if he wins or loses. He comes back home to that kid and he’s going to have a smile on his face.”

The burdens that once lurked inside the gold-medal machine who revolutionized swimming are gone. He’s finally comfortable being Michael Phelps.

“I think the biggest change is just giving me a clearer head in the pool,” Phelps said. “It’s obviously given me a much clearer head outside the pool in my family life, in my personal life. I’ve been able to enjoy life.”

The words — confident, as always, but also self-aware, relaxed, even transparent — hint at his journey.

Four years ago, Phelps didn’t want to swim. He wasn’t training diligently. He wasn’t happy in the pool. He tried to fake it. Phelps managed to win four gold medals and two silvers in London, still performing at a different level than the rest of the world even when he didn’t care.

The medal haul would define the career of any other swimmer. But to Phelps, the effort felt patchwork and half-hearted. He had lurched from medal to medal, world record to world record for the better part of a decade, always focused on what was next. He finally had enough.

Phelps retired for 18 months and wanted nothing more to do with swimming. Longtime rival and 11-time Olympic medalist Ryan Lochte predicted it wouldn’t last. He was right. Phelps couldn’t resist the lure of the pool and returned in April 2014. He gradually started to fall in love with the sport again. He wanted another opportunity to prepare for the Olympics the way he and Bowman believed they should have in 2012. He didn’t want to wonder “what if.”

The pivotal moment, however, came when he was cited for driving under the influence after leaving a Maryland casino in September 2014. Phelps, who pleaded guilty and was sentenced to 18 months of probation, enrolled in a 45-day treatment program in Arizona. This wasn’t his first run-in with trouble outside of the pool. Ten years earlier, Phelps was arrested for DUI and a tabloid published a photo of him in 2009 inhaling from a marijuana pipe. The difficulties seem to have receded into the past.

After the troubles, he reconciled with his estranged father. Phelps and his on-again, off-again girlfriend, Nicole Johnson, were engaged in early 2015. He started training with a new seriousness, not the half-in attitude during the initial stages of his comeback, and recorded the world’s top times in three events in 2015.

“Whatever I’m holding inside of me I’ve been able to get it out and start fresh,” Phelps said recently. “It’s an incredible feeling.”

Phelps started to sound different too. He didn’t dodge phone calls. He tried to be more open, more engaged in every area of life. He started to appreciate what he accomplished in the pool in past years, started to believe that his life seemed like a dream brought to life.

Then Phelps became a father.

“I can just see how happy he is and you can see it every day when he comes into practice,” three-time Olympian Allison Schmitt, who is close to Phelps and Johnson, said recently. “It’s like he’s a new person.”

Nicole held Boomer, wearing noise-canceling headphones, during the 400-freestyle relay that elicited an ear-splitting roar in the stadium as midnight approached Sunday.

Phelps’ powerful stroke on the relay’s second leg put the U.S. in front for good. During the medal ceremony, he told the three other members that it was OK to cry. Phelps grinned on the medal stand, didn’t shed any tears himself and looked as if he was exactly where he wanted to be.

nathan.fenno@latimes.com

Twitter: @nathanfenno