Jordin Sparks isn't shy about showing off her new bikini body.

The 21-year-old American Idol champ posted a picture of herself on Twitter Sunday wearing an itsy-bitsy two-piece that showed off her impressive abs.

How did the "Battlefield" singer, who goes on tour with NKOTBSB this summer, get into such great shape?

"Something just clicked with me, and instead of sitting around talking about it I said, 'I'm going to go hike that mountain!' And it continued.  I've been hiking and I've done a couple of runs," she told Us Weekly last month. "I also do Zumba. It's so much fun!"

Perhaps Sparks, who insists she doesn't diet, got inspired by Oscar winner Halle Berry, 44.

"She is perfect! I think she is beautiful. For me being 21, and then seeing Halle Berry look as good as she does, I think I'm going to look as good as that when I am that age," she told Us. "She is gorgeous and flawless and it's nice to see someone who is confident like that."