Zac Efron didn't recognize himself after putting on 18 lbs of muscle for his new movie.

The 24-year-old actor bulked up to play a war veteran in The Lucky One and admitted he was impressed with his own will power.

He told Men's Health magazine: ''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 will power to actually do it. And I'll always have pride around the sense that I can.''

Although the High School Musical actor claims he doesn't have any special talents, he thinks his willingness to work hard has played a huge part in his successful career.

Zac added: ''I could pick up almost anything. If you put it in front of me, I could always find a way to tackle it. [While training for The Lucky One] I'd get this strange sense of power as those weights increased. I was never a natural at anything, but I could always outwork everybody.''