By Breaking Celebrity News Staff

Guess who's ready for summer?

Yes, Demi Lovato is in the best shape of her young life, as the Disney beauty tweeted a link to the pic on her website looking healthy and fit in a white bikini.

"I've been working so hard to get healthy and fit.. I can't believe I'm about to do this but I'm so excited.. Here's my bikini time body!" she wrote.

The 18-year-old brunette has been on the comeback trail after dropping out of sight upon leaving her international concert tour with the Jonas Brothers last November to enter rehab for "emotional and physical issues," according to her rep.

She’s since admitted publicly to battles with issues such as c