Celeb Sweat: Blake Lively

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Filming this summer's 'Green Lantern' not only changed Blake Lively from a blonde to a brunette,but it also changed her body. After her bodyguard urged her to make the hair color change for the role of Carol Ferris, she also stepped up her workouts. Shape.com points to intense circuit training five times a week as well as core work with planks and a stability ball. The new face of Chanel's Mademoiselle handbags, Blake flaunts her 23-year-old physique and newly red locks with considerable style. She was recently seen sporting short-shorts in France at the Cannes Film Festival.

Hottest Spot: Legs

Along with the usual squats and lunges many stars do to stay in shape, Blake reportedly adds bursts of squat jumps for better results.

Guilty Pleasure: Crepes with Cream Cheese
Trainer Bobby Strom tells UsMagazine.com, "The Greek fest that she made... crepes with cream cheese in them... we could only eat half of it. She ate all of hers and then went back and ate somebody else's half."

Favorite Sport: Flag Football
Though she admits to cheerleading in high school, her more recent sports stint was flag football with then-boyfriend Penn Badgley at DIRECTV's 3rd Annual Celebrity Beach Bowl.