Julianne Hough's secret to her amazing body is right on her wrist

We finally know the secret to Julianne Hough's incredible body -- and it's right on her wrist.

The 29-year-old blue-eyed beauty has been stealing our hearts since age 11, when she was cast as an extra in the first Harry Potter film (though we only recently made the connection).

Since then, she's starred in Grease live, the Footloose remake and as a beloved multi-season judge on Dancing with the Stars -- and she's been giving us major dance envy, fitness inspiration and the definition of #relationshipgoals along the way.

While she grew up dancing, it's hard to imagine that Hough didn't always maintain such a lifestyle, especially in her teen years. "When I stopped dancing and I got a little bit older, my whole body was changing so I had to refigure out how to be healthy and create a new lifestyle," she explained.

Some of these changes were specific to her diet, and others were specific to her fitness routine. Hough joked, "When you're a kid, you can go eat fries and chicken fingers forever. But now, oh man, you feel it immediately."

See more of Hough throughout the years:

Even on Dancing With the Stars, Houghs was adamant about maintaining that constant movement. "We're dancing all day every day. It's not like you come in for an hour -- you come in for 6 hours. The cardio is great too because you're doing short spurts so you're using every single tiny muscle in your body and the quick bursts keep the fat burning throughout the day." We were quite surprised to learn of this time commitment, but that's what it takes to be a star.

Aside from dancing -- and especially since she's not returning to the ABC hit -- she sought to test out different workout routines to figure out what she liked. "At 26, I figured out my constant workouts of what I like and change it up. So, I do yoga, cycling, dance cardio, I do boxing. I get quite bored so I like to change it up," she explained. "I do all that and I have consistent eating habits."

If you follow Hough on Instagram, it's hard to imagine that she has time for all those activities -- but she's letting us in on a little secret. Whether she's going on a long run or dancing while washing the dishes, it's the Fitbit that keeps her in check.

"The first thing to getting healthy is to get up and move. The Fitbit to helps you, reminds you," she exclaimed. "When I have a reminder and I see I've only done 4,000 steps, I know I have to get up and move." Even when she's busy, she manages to squeeze in a workout here and there -- always tracking her heart rate and steps.

"If I'm doing my hair or brushing my teeth, I'm constantly moving. So I'll be doing squats or leg lifts, butt raises or I can do my obliques." All of that movement is tracked right on her wrist.

Hough admits she's competitive, but that's why she connects her Fitbit to her friends and family (especially husband Brooks Laich) and friends -- it's just one of the many features that keeps you in tune with your daily habits. "We have our own separate workouts but once we get together it's something like going out on a hike or a run, something outdoors and adventurous," she said.

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She even uses the Fitbit to track her sleep movements, too -- all of that (somehow) packs into one sleek bracelet, a design even Hough is amazed by. It doesn't hurt that the Fitbit doesn't look like a high-tech fitness tracker, either, but another piece of jewelry. She explained, "It's such a fashionable wristband, too. Right now I'm wearing the FitBit Alta HR, which is super slim and sleek, and the bands on it are interchangeable so you can change the different styles and colors."

For more on how Julianne uses Fitbit in her everyday life, watch the video above.