The pop princess celebrated her 34th birthday at Disneyland with fiance Matt Rutler on Wednesday night.
Sporting a black baseball, red plaid button-down, and black Mother Tucker leggings from Belly Bandit, the "Beautiful" singer put her slim post-baby bod on display as she walked through the theme park.
It didn't take Christina much time to lose those pregnancy pounds!
She gave birth to daughter Summer Rain just four months ago, and she's slimmed down by practicing yoga and sticking to a clean, portion-controlled diet.
"Everything is about moderation," a source told E! News. "She will have cheat meals occasionally too. Running after Max also is helping her burn some extra calories. There's never a quiet moment, Max is very active!"
That said, Christina's main focus hasn't been shedding the weight. The hot mama "is all about family right now, that's what her priority is."
Aguilera will return to the red chair on season 8 of "The Voice" after taking time off since August. No word yet on when her next baby—we're talking an album here—will drop, but we can't wait to hear what she delivers.