I asked Matt Damon's personal trainer exactly how he got him in shape for The Odyssey — here's what I learned

Nolan decided what "they" wanted him to look like, which was muscular but lean. “You’ve been living on a boat for 20 years, you’re…cut, very low body fat kind of look...That’s what we wanted to hit going in.

“We had about five months together, but I’ve been working with Matt for four years. We had a solid five-month block for him to get ready to shoot, and then he had to maintain for the rest of the shoot.”

“It was mostly that he had to lose the fat…Matt loves to work out, he’s already been in pretty good shape.

“He had enough muscle to make the part look good; he just needed to trim the fat back...The whole workout plan was about preserving the muscle he had, while losing weight.”

“We did upper and lower splits. In an ideal week, we had upper and lower splits; we’d do two upper and two lower days, then we’d have a cardio or metabolic day...If we couldn’t get five sessions in, we’d have two full-body days.”

In a "perfect week," they'd be hitting two upper-body, two lower-body and a cardio day like an uphill walk. And on the uppers, we’d be able to hit most things. Dumbbell bench (press), supported rows, pull-ups, pull-downs, horizontal and vertical press. We’d round out with our isolation work, like biceps, triceps, flys, reverse flys.

"In a day, we’d be looking at eight movements, mostly staying in that 8-12 range, although sometimes we’d go up to 15. Sometimes we’d go as low as 5-6 (reps) for strength work."

Stump tried to keep "two to three reps in reserve."

“I didn’t really want to burn him out on any given workout. We’d be going, Monday, Tuesday, Wednesday, Thursday, Friday, and he’d have two days off on the weekends.”

Stump was big on recovery, making sure there was enough time for recovery before training again.

“We sort of planned for what we could do. It was variable based on location and how much time he spent filming.

"You might have a gym...Sometimes you might just be doing bodyweight work and it's really minimal to support what you have." By that, he means calisthenics and anything that could be done to support his training outside of filming.

"For him, it's mainly look, but for me, I'm always thinking about the physical demands. I'm asking him about, 'What kind of scenes are you going to be filming, and what are they going to ask you to perform?"

Thankfully, a well-rounded strength program hit most of the markers and took care of most of it.

"I think the high-intensity intervals on the versa climber...probably not as much as I'd liked, but you take what you can get!"

"I'm always changing and pivoting based on what is working or not working," Stump says. Damon could have had a rough night's sleep, so the super heavy lifting is probably not going to be the focus for that day.

Sometimes, it might be that they have five days together, then schedule changes mean three days, and you're combining days to hit the most important things. Stump mentions that on these occasions, he tries to "front load" them to make them the most important part of his sessions.

"We kept it basic... That's what we had in his gym, and I would have probably kept it basic anyway.

"We had a trap bar, so we could go heavy with that, and we had heavy dumbbells up to 100lbs... We didn't really have a way to do a heavy squat. That was the only thing I would have liked to have that we didn't have. But we were able to do heavy Bulgarian's, trap bar deadlifts, and RDLS."

Stump is principle based.

"You need to do something that is repeatable." By that, he means only 20 minutes a day in the gym is better than throwing 60 minutes at it once per week.

"Whatever that is for you, find something that is repeatable and you continue to do. Find something that is safe, that you feel confident with. And then you need to work hard enough that you're close to failure. You need to get close, that two-three rep range."

Over time, he says you'll get results.

"I think a bit of both."

Stump says there are phases in your life, and you should listen to them. "My gym routine supports the things I want to do in my life.

"Maybe there's a through-line here about motivation, and having clear motivation and strong motivation.

"We wanted it to be a little more raw," Stump says about the motivation behind Damon's final look."