The secret's out: In a new video, model Iskra Lawrence shows off exactly how she works her core, with a killer routine we can't wait to steal.

It all starts with an impressive jump rope warm-up that's sure to please your inner kid. Lawrence skips through high knees, side-to-sides, and criss-crosses until she's broken a sweat (and laughing). Then the body-positive advocate moves on to a five-move circuit that's totally doable in your living room.

First up: 30 reps of alternating heel touches (aka penguin crunches). Lying on her back, with her knees bent and feet on the floor, she touches her right heel with her right hand; then touches her left heel with her left hand.

Next comes a set of 30 toe crunches. With her legs raised at 90 degrees, she reaches up toward her feet. “I like any exercise that’s a challenge, so the challenge in this one is to try and touch your shoe laces,” Lawrence explains.

The third move is the bicycle crunch, to engage her "whole core." As you twist to get your opposite elbow to your opposite knee, use slow, controlled movements, she says: “Start with control, then you can build up speed and build up reps." And remember to breathe.

"I'm starting to feel the burn now!" she says as she finishes another 30 reps.

About halfway through the workout, Lawrence breaks out a "stretchy band," though she says you don't really need it for the next two exercises. "It just adds resistance," so you have to work a bit harder, she explains.

Start by lying on the ground, and placing your feet in the handles, with the band anchored to a hook or post behind and slightly above your head. Keeping your legs straight, lower them toward the ground. Then then open your legs to the side and slowly raise them to 90 degrees in a circular motion.

"With control always keeping your mind on your abs, making sure you're always breathing, do the biggest circles you can," Lawrence says. Not only are you firing up your core, but also your inner and outer thighs. After 10 reps, reverse the movement (so you're lowering your legs to the sides), and do 10 more reps.

RELATED: 24 Fat-Burning Ab Exercises (No Crunches!)

In the final move, Lawrence zeroes in on her lower abs. With her feet still in the handles of the resistance band, she starts with her knees bent and to the sides of her chest, then pushes her legs out until they are straight, and a few inches above the floor. "It's almost like you're doing breast stroke swimming" she says. "It works all the little muscles in your core."

Lawrence says she does ab workouts like this one at least three times a week. And on a normal day (when she's not filming a sweat sesh for YouTube), she does each ab move between leg exercises. 

Lawrence accompanied her video with an Instagram post explaining that she loves “experimenting and incorporating Pilates inspired moves into my AB exercises.” Ready to mix up your own core workout? Give her circuit a go.