Beyonce: "I Feel Best" When My Body's "Still Curvy"

Beyonce Knowles struggles to keep her bootylicious body.

"I'm not one of those people who doesn't have to work at it," the singer-actress, 27, tells the June issue of Self magazine. "I can't eat what I want, and I can't not go to the gym.

"I'm trying to do as much cardio as I can, so if I have a really long day of dancing [in rehearsals], then I'll run maybe three miles," Knowles told the magazine a few days before her I Am... tour kicked off.

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"If not, then I'll run 6," she continues.

And that doesn't include her weight routine.

"I'll put on a song that I really like and do [biceps curls with] 5-pound weights [for] the whole song and just try to burn out," she says.

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But she doesn't want to look too gym-toned.

"To me, sexier when it doesn't look like you go to the gym. If you look like you've been spending a lot of time in the gym, then it just looks like you spend a lot of time in the gym," Knowles says.

"So I never want to get to that point where it's not natural," she goes on. "I think it's important to feel like a woman, as well as look like a woman."

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She tries to avoid weight extremes as well.

"I feel best when I'm not really thin and not really heavy, like now, when I'm still curvy," she tells Self. "I really believe that everyone is supposed to be different, and whatever is a natural weight for you is usually what looks best."

Knowles admits "there are no quick, easy secrets.

"The truth is, it's a lot of sacrifice. It's more about your mental strength than physical strength," she says. "You have to push yourself. It doesn't matter what trainer you have. And it doesn't matter what program you're on. You have to be healthy and make the right choices."

To say motivated, Knowles keeps a painting of an Oscar at the gym -- so when she's on the treadmill, she's running toward her goal.

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"I look at it, and I'm like, 'OK, I have to stay in shape,'" she says.

Her second tactic: shopping. "I buy something too small and then say 'I have a reason! I need to wear these jeans or this hot dress!'"

And when she's on tour, she just needs to glance at her Thierry Mugler costumes to keep her eating in line.

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"[All it takes is to] do a fitting and see that my costume doesn't fit anymore," she says. "I know I have to keep things in all the right places!"

But every once in awhile, she can't resist pigging out.

"When I'm completely overwhelmed and tired, comfort food helps. I'll want to have some ice cream. Or when the tour is behind, I'm like, I just want some Krispy Kremes!" she says. "There's too much good food out there to never indulge."

See photos of stars stuffing their faces.

When she's not touring or shooting a movie, she relaxes her diet.

"When I'm off, I feel like I've earned [the right] to eat what I want, and I give myself a certain amount of time," she says.

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