The former Mr. Universe grew close with Manganiello on the set of the upcoming film, about a team of law officers who raid a drug cartel's safe house, and he even gave the 36 year old expert tips on beefing up for the camera.
Manganiello tells U.K. publication Men's Health, "We had a photo shoot for the movie poster. I was wearing a sleeveless top, crossing my arms and flexing. Arnold came in and said, 'I see you're flexing your biceps. Don't do that. Keep it loose and (with crossed arms) put the other hand back to push (the muscle forward) - you'll get an extra three inches.'"
The Magic Mike hunk admits Schwarzenegger was like a mentor to him.
He adds, "Arnie was a hero to me. He's the reason why every guy of our generation started going to the gym. To film with him for four months was awesome. And he still trains every morning."