Kourtney Kardashian Shows Off Her Slim Bikini Bod Just 5 Months After Giving Birth

by Antoinette Bueno 1:20 PM PDT, May 08, 2015
Photo: FameFlynet

How does she do it?!

Kourtney Kardashian is back in bikini bod shape again, less than five months after giving birth to her third child, Reign Disick. The 36-year-old reality star was snapped on vacation in Mexico on Thursday, looking fabulous in a black high-waist bikini.

Photo: FameFlynet

Kourtney, Scott Disick, and their three children -- Mason, 5, Penelope, 2, and four-month old Reign -- joined Girls Gone Wild founder Joe Francis and his girlfriend Abbey Wilson for their relaxing getaway. The vacation is a family affair, as Joe and Abbey also brought along their seven-month-old twins Alexandria and Athena.

PHOTOS: Hollywood's Hottest Bikini Bods

Kourtney's been spending her time "relaxing, playing with the kids and lounging in the sun," an eyewitness tells ET, also noting that she "looks great." The eldest Kardashian sister has made no secret about working hard to get her pre-baby body back, and two weeks ago, revealed that she's already down to 116 pounds.

"I'm 5 feet tall, so everyone relax I'm on a workout kick, trying to bring some Monday motivation," she Instagrammed alongside a picture of her scale.

💪🏼 it's Monday! Ps: I'm 5 feet tall, so everyone relax I'm on a workout kick, trying to bring some Monday motivation.

A photo posted by Kourtney Kardashian (@kourtneykardash) on

Kourtney recently talked to Harper's Bazaar about getting back into shape since giving birth to baby Reign in December.

"I like to take my time and not try to put too much pressure on myself, but it's hard," she told the magazine. "I think I forget every time -- you give birth and you want your stomach to be flat. It does take a lot of work, but I usually start slowly by going on walks with the baby... now I'm in full force."

Though obviously, there's no magic trick to losing the weight. Kourtney exercises and eats healthy to get results.

"I've been working out with a trainer, and having somebody else to work out with really helps motivate me," she shared. "Some days Khloe will join me, or I have a girlfriend I've been working out with -- just setting that trainer session and knowing I'm not going to flake. I also try to eat really clean and at home as much as I can."

VIDEO: Kourtney Kardashian Shares First Pic of Her Adorable Son Reign!

Kourtney's never been shy about documenting her life as a mother of three. Watch the video below to see her pose with her breast pump in Las Vegas after celebrating her 36th birthday!