Beyonce Knowles may be known for her flawless curves, but if you think the sexy singer’s enviable figure comes naturally, think again.

In the new issue of SELF magazine, on newsstands May 26, Knowles, 27, opens up about dieting, sacrifice and what it takes to keep her curves in check.

“I’m not one of those people who doesn’t have to work at it,” she says. “I can’t eat what I want, and I can’t not go to the gym … There are no quick, easy secrets. The truth is, it’s a lot of sacrifice. It’s more about your mental strength than your physical strength.”

PHOTOS: Click here for exclusive SELF shots of Beyonce Knowles.

So what does it take to stay in Beyonce shape?

“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 only run maybe 3 miles. If not, then I’ll run 6.”

And then there is the weight training.

“I’ll put on a song that I really like and do [bicep curls with] 5-pound weights the whole song and just try to burn out,” she adds.

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But don’t think the star is out to go to crazy.

“To me it’s 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. I think it’s important to feel like a woman, as well as look like a woman.”

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