We're officially impressed!

Michelle Monaghan may have turned 39 yesterday, but she looked more like an 18-year-old while vacationing in Tulum, Mexico, for her birthday.

The actress, who has the body of a Victoria's Secret model, posted an adorable photo of her doing a spirited cartwheel on the sand — which we should point out is NOT easy!

michelle monaghan

Look at that form… Those pointed feet…

We may be distracted by her killer cartwheel skills, but we're more interested in Michelle's killer physique, which she kept in shape even on vacay.

"RUNRISE #trainingforahalfmarathon #evenonmybirthday," she captioned another pic that showed her in the middle of a jog along the water.

michelle monaghan

Michelle, who has a six-year-old and two-year-old with husband Peter White, previously told 'Women's Health' that she's "never been on a diet."

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"I don't think they make sense. Ultimately, it's eating sensibly," she told the mag. "But if I'm at a restaurant, all bets are off!"

PREACH, girl!