Guess who has been spending their time in the gym!Zac Efron shows off his beefy biceps on the cover of the newest issue of Mens Health Magazine. The Seventeen Again actor has made a major body improvement in the past year. Now 24 Zac Efron is beginning to gain more adult fitting movie roles. This is not the Zac that Vanessa Hudgens was with, but we love this zack too.What do you think about the cover, leave a comment below.