Kourtney Kardashian Reveals How Much She Weighs After 3rd Baby

"I'm on a workout kick," the reality star said.

ByABC News
April 28, 2015, 12:08 PM
Kourtney Kardashian's 36th Birthday Party held at 1 OAK Nightclub Las Vegas, April 18, 2015, in Paradise, Las Vegas.
Kourtney Kardashian's 36th Birthday Party held at 1 OAK Nightclub Las Vegas, April 18, 2015, in Paradise, Las Vegas.
Xavier Collin/Image Press/Splash

— -- Kourtney Kardashian just gave birth to her third child Reign -- but she looks to be bouncing back rather quickly.

Kardashian and her partner Scott Disick welcomed their second son and third child on Dec. 14. Just over four months later, the reality star, 36, took to Instagram to show off some major weight loss.

"It's Monday! Ps: I'm 5 feet tall, so everyone relax I'm on a workout kick, trying to bring some Monday motivation," she wrote next to a pic that says she weights 116 pounds.

Reign Aston joined son Mason, 5, and daughter Penelope, 2, late last year and on Dec. 21, she introduced the little guy to the world.

"Madly in love with my little Reign Aston Disick," she wrote next to a photo holding his little hand.