Prince of Persia: The Sands of Time

Jake Gyllenhaal, "Prince of Persia: The Sands of Time" (2010)

The Strapping Story: Dastan (Gyllenhaal), a frequently shirtless and straggly haired sixth-century Persian prince, must stop an evil nobleman (Sir Ben Kingsley) from getting his hands on a device that can destroy ... morethe world.

The Hard-Bodied Breakdown: Audiences won't get to see Gyllenhaal in his pumped-up state until May 2010, but, judging by the trailer, the wait will be worth it. "I guess I've gotten buff," he downplayed to "Entertainment Tonight" during filming. "There's a lot of acrobatics in the movie -- a lot of running up walls, and jumping on things and parkour [basically, running full-speed at an object and bouncing off it]. So it requires muscularity, but it requires a lot of aerobic ability, too." The actor's training reportedly included wearing a 20-pound jacket while running and doing uphill sprints followed by sit-ups upon reaching the top (we got winded just typing that).

(Walt Disney Pictures)