While appearing on "Hot Ones," the actor discussed his transformation, saying his "Baywatch" body was incredibly hard to maintain.
"That was actually a really important time to do 'Baywatch' because I realized that when I was done with that movie, I don't ever want to be in that good of shape again. Really. It was so hard," he said. "You're working with almost no wiggle room, right? You've got things like water under your skin that you're worrying about, making your six-pack into a four-pack. [Stuff] like that, it's just not… It's just stupid. It's just not real."
While Zac notes that he never wants to get that fit again, he would consider doing it for the right role.
"I'm happy that it worked. I'm happy that it got me through it. I may do it again if it was something worthwhile, but we'll wait till it gets to that," he said on the popular Internet show. "I'm good. Take care of your heart, take care of your brain and you're good."
Zac, of course, is no stranger to fitness — he even has a show called "Gym Time" on his YouTube channel. On the show, he works out with famous faces from all industries. Previous workout buddies have included professional athletes, actors and Victoria's Secret models.
"For me, athletes are movie stars. When I get to meet or hangout with someone who's an inspiration to me throughout whatever their art or craft is, that's really fun," he said on "Hot Ones."
"If they want to train with me, unreal! I'm getting to peek behind the curtain and sort of just have fun with them and see them in their element, because that's all they do. They train and some of them are savage," he added.