By Breaking Celebrity News Staff

Five years ago, she was a hot mess; now, she's just hot.

The resurgent Britney Spears showed off her super-sexy body in a tweet Thursday, writing, "Having some fun in the sun… don’t want summer to be over!"

It's clear the mother-of-two has been hitting the gym regularly, as in the new pic, she shows off a flat tummy and well-toned legs in her two-piece green floral bikini.

The 30-year-old Toxic singer will serve as a judge on Simon Cowell's The X Factor this fall alongside Demi Lovato and L.A. Reid.