updated 07/09/2007 AT 01:00 AM EDT
•originally published 07/09/2007 AT 01:00 AM EDT
An action star at 52!
"Bruce didn't have his prom last week," says Gunnar Peterson with a grin. Still, says the trainer who helped whip Bruce Willis, 52, into shape for Live Free or Die Hard, "you don't see many in his age bracket knocking it out at the gym with his dedication." To get back into fighting form after a 12-year Die Hard hiatus, Willis did hour-long cardio and strength sessions nearly every day for three months before filming. On set he worked out during lunch. Peterson was impressed: "His thing is being able to do what the role requires." In this case that meant having a body that looked credible hanging from moving vehicles, dodging bullets and trotting around in an ever-more-torn shirt. Though you might guess that once stars hear "that's a wrap," they exhale and head for the sofa, Peterson says Willis kept up his routine. "What if the director decides to reshoot?" Eventually, Willis may let himself go a little. "It's not natural to stay completely shredded year-round."
A KID STAR GROWS UP—AND SLIMS DOWN
Watching later episodes of the '90s teen TV hit Boy Meets World in 2001, "I was amazed at how big I let myself get," says Danielle Fishel, who played brainy gal pal Topanga. Since 2005 Fishel, now 26 and a correspondent for The Tyra Banks Show, has shed 28 lbs. using the NutriSystem diet and will appear in ads for the prepackaged meal plan this month. "I'm never going to look like Gisele [Bündchen], but I'm happy with where I'm at."
"Whenever I had to film an intense scene, I'd run around the lot to get out of breath. I lost about 10 lbs. in a couple of weeks"
—LIV TYLER, on shooting the horror film The Strangers, out later this year.