James Brolin, 82, Shares His Secret to Staying Youthful: Working Out in the Water — with Weights

Brian Bowen Smith

James Brolin is in great shape at 82 years old — and he credits weighted water workouts, thanks to surfer Laird Hamilton.

"I'm at a [dinner] party at a friend of mine's, and one night Laird Hamilton and Gabby Reese [were] there," Brolin shares exclusively with PEOPLE over lunch near his Malibu home.

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At the time, Brolin had been feeling unhappy with his appearance and was looking to change his diet and fitness routine.

"Laird said, 'Why don't you come on up to the pool and work out with us on Tuesday, Thursday and Saturday?' " the Sweet Tooth narrator recalled. "So I went, 'Yeah, okay, great.' I didn't."

One morning, though, he changed his mind and decided to give it a try. "I got up early and I said, 'I'm going up there.' Then I became a regular and it changed my life working out with weights under water."

At first, Brolin almost gave up on the workout. But he trusted Laird to guide him through the unique aquatic plan.

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"His deal is, 'Oh, do you want to breathe?' " Brolin shares with a laugh. '"You have to get to the top.' I said, 'But I got the weights. I can't.' He said, 'Yeah, no, you have to take the weights with you.' "

After some practice, Brolin, who's married to legendary singer Barbra Streisand, started to get the hang of things.

"Once you get used to 10 lbs., then we move you to 15 lbs.," Brolin explains. "Then we move you to 20 lbs. and it's a jumping exercise to start. Then next, they've got you swimming the length of the pool with a weight."

Brian Bowen Smith

After a handful of sessions, the Lightyear star was pleased with the transformation, inside and out.

"I started to change," Brolin says. "Everything started to change. I just started to look better. Body, face, eyes, thinking and therefore proving the old, boring thing that exercise really works."

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Brolin also uses detoxing techniques after his workouts to get rid of the extra gunk in his body.

"I have a sauna at home," Brolin says, adding that he tries for at least 40 minutes, three times a week. "All the toxins come to the surface and are gone."

Brian Bowen Smith

But exercise is only part of the feel-good equation — Brolin also follows a healthy diet.

One of his favorites? "Greek salad or Mediterranean salad and a handful of cheese on it," the father of three shares.

But he's not afraid to splurge, especially when his wife of 24 years insists on it.

"We could eat a whole loaf [of sourdough bread] and all she has to do is say, 'Well, you deserve it,' Brolin says with a smile. "And I'll just eat the whole loaf."