With all due respect to Jason Derulo's singing, the first thing you think when you see one of his videos is "Dude can dance." The barrage of fluid contortions, twists, and gravity-defying acrobatics will have you wondering: Wait, did he really do that? But there's no CGI involved—only sweat equity. The 23-year-old Miami native has perfected his moves by spending up to eight hours a day rehearsing steps and another 90 minutes in the gym. "Dance is an amazing workout. It's my main form of cardio," Derulo says, adding that the intricate, fast-paced, high-intensity motions are similar to boxing. "I push it hard until all my stress and aggression is released."

The benefits go beyond the mental: Derulo's six-foot, 175-pound frame is a model of lean, sculpted tissue—shoulders, pecs, back, and six-pack abs. He started building up the muscle memory at a young age. "I don't remember not dancing," he says. "I saw Michael Jackson for the first time and thought, 'What?!' I spent night after night, day after day, trying to get that moonwalk action." MJ's signature step requires a surprising amount of core strength, and Derulo's oft-performed single-arm handstands and back handsprings work his entire upper body—without adding bulk, a dancer's nemesis. "The leaner I am, the more agile I am, the more I can move," he says.

But Derulo has no interest in being waifish. "I want to look like a man, not too skinny or scrawny," he says. That's where trainer Kevin Henderson, who also works with rappers like the Game, comes in. When Derulo is at home in Los Angeles recording (his third album, Tattoos, will be released this month), Henderson guides him through a weight-based regimen that increases muscle endurance and adds definition. Combining the two disciplines has given the singer a body he's proud of. "I used to keep my shirt on at the beach—even in the water," Derulo says of what he calls his "little fat stage." Now, he says with a laugh, "I'll be like, 'It's hot in this restaurant—better take my shirt off.'"

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How To Get Started
The trim, toned body of a dancer is attainable—even if you've got two left feet. These exercises, which Derulo does during his sessions with trainer Kevin Henderson, target the shoulders, arms, chest, and core, prized parts of a breaker's anatomy. Do each in order once, resting 30 seconds to a minute between moves.

1. Roundhouse Push-up
Get in plank position. Shift weight to left side and, keeping right arm straight, bend left elbow, lowering chest toward floor. Bend right elbow as you shift to the center. Then, keeping right arm bent, straighten left arm, moving to right side. Extend right arm to return to starting position. Repeat, lowering to the right side first to complete 1 rep. Do 2 sets of 15 reps.

2. Roll Outs
Get on all fours with knees under hips and hold the handles of an ab roller in each hand. Keep head to knees aligned and elbows straight as you slowly push the ab roller away until chest hovers a few inches above the floor. Return to starting position as quickly as possible. Do 2 sets of 10 reps.

3. Biceps Curls Superset
Hold a 50-pound barbell with both hands, arms extended at sides, palms facing forward. Bend elbows, drawing barbell toward chest. Lower. Do 5 reps. Rest for 30 seconds, then do 4 reps. Repeat, reducing reps by one until you reach 1 rep, then build back up again. That's 1 set. Do 2 sets.

4. Unstable Single-Arm Shoulder Press
Kneel on a stability ball and hold a 20-pound dumbbell in right hand, elbow bent, palm facing forward. Extend right arm, pressing dumbbell toward ceiling. Lower. Do 8 reps, then switch sides to complete set. Do 2 sets.

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The Best Places to Dance Your Ass Off
Set the floor—and your metabolism—on fire with these classes.

Broadway Dance Center (New York City)
Good luck finding a spot among the fashion types during sessions led by Sheryl Murakami (she's toured with Lady Gaga).

Lou Conte Dance Studio (Chicago)
Of the 70-plus courses held weekly, the can't-miss class is hip-hop with Trae Turner, who's danced with Kelis and Ne-Yo.

Millennium Dance Complex (Los Angeles)
Justin Timberlake and Usher have dropped by this dance institution, which offers styles from ballet to breakin'.

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Jason Derulo Q&A
The R&B star shares workout tips, dance moves, and stories about growing up not so fit.