Britney Spears Shows Off Sexy Stomach in Purple Bikini

Britney Spears and sons Jayden James and Sean Preston Credit:

Brit's got a bangin' bikini bod!

Taking a break from her role as X Factor's newest judge, Britney Spears spent the July 4 holiday with her fiance, former agent Jason Trawick, 40, and sons Sean, 6, and Jayden, 5, soaking up the sun in Maui.

"Happy 4th of July from the Aloha State!" Spears, 30, tweeted Wednesday. Later, the pop superstar -- flanked by her sons in swim trunks -- showed off her toned bikini bod in a purple swimsuit in a photo posted to her Twitter page. "Getting ready for some pool time! Having a blast xxoo" she wrote.

An eyewitness in Maui tells Us Weekly Spears spent quite some time poolside during her family vacation. "She had a cabana by the adult pool all day. No kids are allowed there but she had her kids with her," says the insider, adding that the trio also enjoyed the hotel's waterslides. See more photos of Britney's Hawaiian vacation.

Maintaining her fit figure is often a challenge for the pop star, who tells the U.K.'s Stylist she struggles to stay motivated. "Trying to get up and go work out in the morning [is hard]," she admitted. "But once you get up and do it you feel like you've conquered the world."

Working out allows Spears to indulge guilt-free in her favorite food: "Chocolate. Definitely chocolate."

"I love Skors, with the caramel in the middle, and every once in a while if I'm really hungry then a Snickers bar is good," Spears says. "And M&M's are great, Hershey's Whoppers are great, Raisinets. . . Twixes are great, too. And the new Hershey's Cookies 'N' Creme."