It's not hard to understand why Jessica Chastain headed to a motocross course to blow off steam after the Cannes film festival in May. Not only had two of the 30-year-old actress's movies screened there—Terrence Malick's The Tree of Life and the psychological thriller Take Shelter (out September 30)—but a bidding war had broken out over a third, John Hillcoat's bootlegging adventure The Wettest County in the World, to be released in 2012. Plus, she'd recently completed four other movies due to hit theaters by year's end. But Chastain's excursion left her with more downtime than planned. "The only way I could get myself to rest was to get into a motorcycle accident," jokes the crimson-haired Juilliard grad, who's recovering from ACL surgery. Chastain's willingness to push her body has proved professionally advantageous: She plays an ass-kicking Mossad agent in the spy thriller The Debt (out August 31) and, in October, a rodeo queen turned detective in the serial-murder saga Texas Killing Fields. What were the demands of playing a buxom Mississippi housewife in the 1960s race drama The Help? Adding curves. "I'm vegan, so there's not much I could eat to gain weight—I would microwave soy ice cream and drink it," Chastain says. "Also, I had a pretty good push-up bra."