"I'm running more, I swim a lot, and I box a lot," says Lutz, 26, who recently moved closer to the beach in L.A., where he enjoys doing shirtless outdoor workouts.
BOO BOO STEWART
The 17-year-old actor-singer and martial artist has a secret weapon in his quest to stay fit-his mom's a personal trainer.
Lautner's trick for bulking up? "Eating thick, heavy food every two hours," he told USA Today
. "That was really tough for me. Three protein shakes a day. Ugh."
When it comes to exercise, the guy who plays the volatile werewolf Paul has the heart of a beast. "He was intense," says Mariko Hammett, a personal trainer at Seattle's 24 Hour Fitness, who worked with Meraz, 26, while he was filming Breaking Dawn
. "He's one of the most able clients I've ever had." Hammett would have Meraz do a range of exercises from shouldering 80-lb. sandbags to dragging tires. Says Hammett: "Alex's workouts were grueling. He was awesome."