Matt Damon's advice to Josh Hartnett while filming 'Oppenheimer' was ‘so unhelpful’

Josh Hartnett revealed some "unhelpful" advice Matt Damon shared with him while they worked together on the Oscar-winning film "Oppenheimer."

"He gave me a lot of good advice," Hartnett said. "One in particular — one thing that was just so unhelpful: He told me not to gain the weight I’d already gained for the role."

He continued, "I gained about 30 pounds for the role, and he was like, ‘You’re never gonna get that off again, man. Don’t gain weight over 40. You’re going to spend the rest of your life trying to get that weight off and it’s never going to come off because your body is going to want to get that weight back on. You’re just going to keep growing back out to that size, and you’re going to try and get it off, and it’s just going to go back.’ He kept telling me over the course of production."