There's been so much cycling to keep track of, too: More than 70 rides, and he is closing in on 1,000 miles this year and counting.
JPM, NASCAR driver, has morphed into JPM, fitness freak. His quest has even taken him to a pilates studio, where wife Connie convinced him to try a handful of classes.
About the only part of his workout routine he won't detail is exactly how much weight he's dropped. But it's clear by looking at his frame that he's in the best shape of his stock car career. Yes, he was tired of the flab, but not just because he was overweight, but because of what it represented.
He's doing it all with one goal in mind.
"I want to (expletive) succeed in this," he said. "I'm tired of sucking."
Montoya just might turn it around in Indianapolis, because he was back on top of the Brickyard on Friday.
Just like he was when he won the 2000 Indianapolis 500.
Just like he could have been at least two other times in the Brickyard 400.
Yes, it was only the top time in practice, but it's a sign that Montoya will be a contender again at Indy. He needs to be, for the sake of his sanity and perhaps his job. Montoya is in the final year of his contract with Chip Ganassi Racing, where he's won two races in the eight years since he abruptly left Formula One for NASCAR.
His only wins were on road courses, and he's not been to Victory Lane since 2010. Montoya heads into Sunday's race at Indy ranked 23rd in the Sprint Cup standings with three top-10 finishes on the year.
Ganassi won't be pinned down on Montoya's future as driver of the No. 42 Chevrolet.
"We're all trying to get results here. We're just working on results," he said. "Juan has a deep history with our team, and we want to give him every opportunity to do well. All of our drivers who have deep histories with our team, we go out of our way to make sure they are given every opportunity."
The opportunities have been few and far between for Montoya, who won the Indy 500 and the 1999 CART title driving for Ganassi but hasn't found the same success since reuniting with the car owner in NASCAR. Part of his struggles are linked to the rollercoaster performance of the Ganassi organization, which has failed to put together consistent seasons.
The team owner ordered a massive organizational overhaul after the 2011 season, and the results are only now showing.
Montoya, one of the highest regarded drivers in the world when he jumped to NASCAR, admits the struggles have been draining.
"It's hard to keep your head up when things are not going well, and you go to places where you know you can get a pole and run up front and get top-fives, and instead you are running 30th and are the slowest car on the track," Montoya said. "It's hard because I know it's not me."
There's been marked improvement this year, and Montoya contended for wins at both Richmond and Dover. He had the race at Richmond in the bag until a late caution snatched his first NASCAR win on an oval out from under him. He was the leader late at Dover until Tony Stewart ran him down and passed him for the victory.
His wife believes those near-misses have only pushed Montoya harder.
"Everyone was talking about how Michael Schumacher forgot how to drive. He didn't forget how to drive and Juan didn't forget how to drive," Connie Montoya said. "NASCAR is so difficult because all the teams are so close, but so apart, and Juan knew from the beginning that Ganassi wasn't the fastest team. He was ready for that challenge to build up that team, especially because it was Chip and he wants to be with Chip.
"But he's just so frustrated they haven't been able to get their first win on an oval," she added. "Not winning is just the worst part for him. He races because he wants to win, like every driver, and he's so committed. I really think he's much more into it now, that he is up to the challenge. He really, really wants to prove it to himself that he has it what it takes to win in NASCAR."
He demonstrated his commitment by shaking up his routine and Montoya settled on mountain biking as his hobby of choice and has become absolutely devoted to his rides.
His turnaround has wowed those closest to him.
"This is the hardest I've worked, even in Formula One or IndyCar," Montoya said. "Connie says "I can't tell you to do anything else because you can't do anything more."
All he needs to do now is win.
Montoya should have crossed the pesky oval thing off his list years ago, here at the Brickyard. He's had two great chances and both slipped away in the waning laps.
Montoya led 116 laps in 2009 until a speeding penalty on his final pit stop cost him the win. He was also leading in 2010 with 20 laps to go before a late caution sent him to pit road, where he got four tires while everyone else took two. Stuck deep in traffic with little time to make up the ground, Montoya crashed and finished 32nd.
He insisted neither race haunts him.
"I never felt I was speeding," he said. "I felt I did the same speed as all the other stops. Maybe they (NASCAR) looked the other way?"
Montoya goes into Sunday wanting that win on an oval, wanting a NASCAR win at Indy to go with his 500 victory, and wanting to prove this series is the right place for him. No matter what happens the rest of the year, or what the future holds with Ganassi, he wants to stay in a stock car.
"The whole NASCAR thing is fun. The racing is good. Even when you are having bad years, there are weeks you can make something out of nothing and that makes it good," he said. "In Formula One, you look at Williams, they struggle every week and they'll keep struggling until the end of the year. You are not going to fix the problem, they'd love to think they can, and they'll try to fix it, but when you start that far behind, unless you find something radical, you are not going to make up any ground.
"Here, you have cars some weeks that can win races and some weeks finish 30th. I want to win races."
NASCAR Sprint Cup Series
P Sunday, 11 a.m.
TV • ESPN