Erin Heatherton's Secrets for Staying in Supermodel Shape

How does Victoria’s Secret and Sports Illustrated model Erin Heatherton stay in such enviable shape?

First, the 6-foot-tall stunner credits the Ballet Beautiful workout for keeping her body looking toned and lean.

“My body is very athletic, so the exercises that really help my body are things that are lengthening,” Heatherton, 25, tells PEOPLE. “I’ve been doing Ballet Beautiful since 2013, and I’m still in the falling-in-love stage. It re-taught me how to stand, and a different way to hold my weight, so it helps me move as a model as well.”

The model — who recently competed in a Fitbit Celebrity Challenge against Hilary Rhoda to help raise money for the American Heart Association — works out most days of the week, doing a combination of ballet, yoga, Pilates and the occasional SoulCycle class.

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“I like to switch it up,” she says. “It depends on my mood, but I always stay active.”

Her workouts tend to be hour-and-a-half sessions, and when she does something less cardio-driven – such as Moksha yoga – she adds in a 30-minute warm-up on the treadmill where she alternates between jogging and high-incline walking.

While Heatherton loves working out, she explains she also makes sure to give herself days off for recovery. “Your ligaments can only heal through rest, and you have to rest if you want to see the results of all your hard work,” she says.

When she’s getting ready for a big photo shoot, Heatherton sets aside time for invaluable shut-eye. “I’ll make sure the week before that I take time off to sleep enough, which is equally as important as working out,” she explains.

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Of course diet is also a key component to looking bikini-ready.

“I always eat healthy because you don’t want to dig yourself in a hole,” says Heatherton. “The best diet is to focus on what you should be eating, and knowing how the foods you’re eating are helping you be healthier and look more beautiful. What you put in your body is what makes you glow and look healthy and gorgeous.”

Heatherton’s go-to foods include berries, eggs, avocado, salad and fish. “I could eat fish every day,” she says “I love eating fish, and I honestly would always choose fish over pizza!”

—Gabrielle Olya