Kourtney Kardashian shows off her unbelievably toned post-baby abs just six months after giving birth, MSN reports.

In an incredible Instagram post, Kardashian snapped a mirror selfie wearing just a sports bra and super comfy-looking striped pajama pants. She captioned the shot, "Hopped up out the bed, turn my swag on Took a look in the mirror said what's up?" which is a direct reference to the 2009 Soulja Boy song, "Turn My Swag On."

 Hopped up out the bed, turn my swag on Took a look in the mirror said what's up?

A photo posted by Kourtney Kardashian (@kourtneykardash) on Jun 18, 2015 at 11:07am PDT

Judging by the photo, it's hard to believe the 36-year-old is a mommy of three. Kardashian and her longtime boyfriend Scott Disick welcomed ther third child, Reign, last December, according to Us Weekly.

Kardashian sculpted her body by working out 3-5 days a week with fitness trainer Don Brooks and his Donamatrix method. His dished on the type of exercises that helped Kardashian get those abs.

"The plank is a favorite, but we take it to another level opening and closing the legs like scissors while at the same time raising and dropping the hips," he told E Online. "We use the resist-a-bands a lot-the bands are very effective for toning without bulking or injury."

Kardashian heard about Brooks and his routine from Fergie and her hubby Josh Duhamel.

"He just basically kicks your ass for an hour," Duhamel told E Online.