"While I'm walking, I do it. On airplanes, I do it. In cars, I do it – so when somebody asks, 'Hey, can I see your abs?' it's always there," the Jersey Shore star tells Men's Fitness in its December/January issue, on newsstands Nov. 15.
The secret is isometric contractions, which enables him to work out the muscles from a static position, without having to do sit-ups or make any other movement.
Not that he's about to give up the "G" in GTL. "Every day when I wake up I gotta go to the gym," he says. "I arrange my other activities around my workout. I have to organize my mind, body and health first."
The relentless exercise is just one part of Sorrentino's grand plan of self-promotion, which has already taken him from the MTV hit to ABC's Dancing with the Stars – and he doesn't plan to stop there.
"On Jersey Shore, people got a glimpse through a keyhole of who I really am. But the world really started to see me on Dancing With the Stars," he says. "I wanted to let people know, hey, this kid is risking a lot just to show a different side to him. I can play many roles."
He's hoping to make the jump to movies next, and isn't about to start questioning the scope of his talents. "I shoot for the stars," he says. "If I get to the moon, I'm OK with that."