When Kristen Stewart is busy working on a movie, she's happy. It's when she has a break from work that she says she "falls to pieces."

That's how the On the Road actress explains how much she loves acting in an interview with Little White Lies magazine -- given before Stewart was caught cheating on her boyfriend of three years, Robert Pattinson, in July.

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"Oh my god, I f---ing love it so much," Stewart, 22, said of her job in May at the Cannes Film Festival while promoting On the Road. ". . . I'm like, bursting. I should be working. I don't want to take a break. It's funny, on set, I don't have to go to the bathroom, I don't have anything wrong, I'm perfectly fine, so through-and-through. I'm not hungry. I'm literally not even in my own body. They wrap and they send me back to my trailer and I f---ing fall to pieces. I suddenly realize that I've had to pee for six hours. And I'm starving."

(Indeed, it was during a break between film projects that Stewart, 22, had an ill-advised public PDA-fest with Rupert Sanders, her married, 41-year-old Snow White and the Huntsman director.)

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Stewart plays Marylou, the 16-year-old wife of Dean Moriarty (Garrett Hedlund) in On the Road, which is based on Jack Kerouac novel.

"I just really am trying, trying, all the time," she explained about her love of the dramatic arts. "But I like to be scared. I love to suddenly feel out of control. Actors walk around wearing these little tool-belts of acting skills. And I just don't find that interesting to watch. I never want to see someone who clearly can cry at the drop of a hat. That's so uninteresting. And so many actresses are so f--ing crazy. They're emotional wrecks, so they pretend to be these characters. But the emotions aren't coming from the right place. Do you know what I mean?"

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On July 24, Us Weekly revealed exclusive photos of The Twilight Saga: Breaking Dawn - Part 2 star engaging in a steamy makeout session on July 17 with Sanders.

Since the affair, Stewart has publicly apologized to her Twilight costar/real-life boyfriend Pattinson, 26. "She isn't sleeping and she stays up all night crying," a source told Us in the new issue, out now. "She's close to a total meltdown."

This article originally appeared on Usmagazine.com: Kristen Stewart: " I Love to Feel Suddenly Out of Control"