We're so excited! Britney Spears has been engaged to fiancee and manager Jason Trawick since December, and she's finally planning her wedding.

The Mirror reports that Spears is planning to tie the knot once 'X Factor' wraps for the season. She's even dieting to prepare for the big day -- even though we think she looks amazing already!

“She’s put a treadmill into her 'X Factor'­ ­dressing room and is making sure she’s ­jogging as often as she can," a source said. “She’s taking her look ­incredibly seriously and has said she will ­dazzle with her outfits and her body on the live finals of 'X ­Factor.' It’s very much a countdown to the nuptials right now ... we’re ­talking within weeks.”

One caveat about the wedding: Sam Lutfi may try to say that if she's competent enough to marry, then she's competent enough to stand trial in his defamation suit -- something her and her parents' attorneys are desperately trying to avoid.

It will be Spears' third walk down the aisle. Her 55-hour marriage to childhood friend Jason Alexander was annulled; her two-year marriage to Kevin Federline ended in divorce and netted her two adorable sons, Sean Preston and Jayden James.

In any case, the source says that 'X Factor' has given BritBrit more confidence than ever -- and so has her collaboration with will.i.am, 'Scream and Shout.' She recently wrapped filming for the video, and it sounds like a blast. “She had her groove back and she looked and danced ­brilliantly," a source said. “There’s a throw down section where she performs a solo dance on a podium, and all you hear is, 'It's Britney, b----,' and then she dances like crazy. She’s got her groove back. 'X Factor' has given her a new lease of life ...  she wants to show people what originally made her so famous again.”

Congrats, Britney! We're glad to have you back.

Watch the Britney Spears 'Criminal' Video