Taylor Lautner - Personal Trainer Taylor Lautner

Taylor Lautner will become a personal trainer if his acting roles dry up.

The 17-year-old actor - who plays the werewolf Jacob Black on the 'Twilight' film franchise - has reportedly qualified as a fitness instructor because he's worried about job security in the future.

A source told America's National Enquirer magazine: "His self-esteem shot through the roof when he bulked up for 'The Twilight Saga: New Moon' and he wants other people to experience that feeling."

Taylor reportedly took up personal trainer courses online for $200 and finished them on November 22.

The actor - who often appears shirtless in the vampire movies - has since become a heartthrob and found himself inundated with female fans.

Taylor has reportedly realised what great advertising this could be to his future career.

The source added: "He wants to open up his own workout centre one day."

The US star - who put on over 30lbs for his part in the film - said his motivation for the muscle gain was the "movie and the fans".