Going topless for a movie role? Not a problem for Kristen Stewart!

The 22-year-old actress takes it off in her new film, On the Road -- and she didn't have to think twice about doing it. In the Walter Salles-directed film based on Jack Kerouac's classic book, Stewart plays the seductive Marylou, who is the 16-year-old wife of Dean Moriarty (Garrett Hedlund).

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"It didn't bother me," Stewart told MTV News at the Toronto International Film Festival. "You can do no wrong with [Salles]. He puts so much inside of you. In the four-week rehearsal process, it was okay to ask any question, to bring up any story, to really overanalyze everything and intellectualize everything."

"Once we got on set, it was so about just breathing and letting it happen. He put so much trust in us," she explained. "So it was like, 'OK, so I have to take my clothes off?' It's so not a big [deal]."

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While Stewart has no fears about making her topless debut in On the Road, fans are wondering how she'll cope with promoting The Twilight Saga: Breaking Dawn -- Part 2 with estranged boyfriend Robert Pattinson.

When the Twilight star was asked by a reporter on Sept. 8 how she and Pattinson would handle reuniting in November, Stewart said, "We're going to be fine. We're totally fine."

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But a source close to the British heartthrob tells Us Weekly, "He's leaning toward not taking her back." Stewart was caught cheating on her bofyriend of three years in mid-July with her married Snow White and the Huntsman director Rupert Sanders, 41. Still, Stewart hopes she can change Pattinson's mind. "She's being really aggressive and isn't ready to let go," a Stewart pal says. "She's really ashamed of what happened."

This article originally appeared on Usmagazine.com: Kristen Stewart: Going Topless in On The Road Was "Not a Big Deal"