RobertPattinsonShirtlessWater230.jpgTaylor Lautner has gained fame for his fab bod, as seen in the Twilight series, and it turns out Taylor's pecs have taken a toll on co-star Robert Pattinson!

Pattinson might be known as heartthrob Edward in the series, but he got nervous for the upcoming film, Breaking Dawn: Part I, when he found out he'd have to do shirtless scenes!

Pattinson tells Mexican magazine 15a20:

    "You ... have to worry about how you're going to look. I had never been so worried about that before, but after seeing how much Taylor [Lautner] works out for the movies, I thought, 'Well, everybody is really going to judge me now. I always tried to think about positions where I could tense the muscles, and suck in my belly. I think I just gave the most vain answer I could come up with."

Rob says he worked out for Breaking Dawn, but he couldn't quite achieve that Lautner physique!

    "I thought, 'Okay, it's the last one [movie], I'm getting a six pack,' and I tried, but it's very hard. I worked out so hard for six months, so after filming the sex scene, the first thing I thought was, 'Time to eat!'"