Pic! Zac Efron Flexes for 'Men's Health'

"The Lucky One" star Zac Efron ignites the May cover of "Men's Health" with his incredibly muscular arms.

When Zac was asked about training for his upcoming Marine role, he said, "By the end of the movie I didn't recognize myself. You hear about guys like Christian Bale who dive into it and are really able to transform. I've always wondered if I had the willpower to actually do it. And I'll always have pride around the sense that I can."

Efron adds, "I was never a natural at anything, but I could always outwork everybody."

Read the full story in Men's Health, on newsstands April 17.