To really make that booty pop, you'll have to mix up your exercise routine. "The biggest mistake people make is not working this complex muscle group from enough angles," says Gunnar Peterson, who trains Minka Kelly and Sofia Vergara.
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Power Squats. "Squats are essential to building an amazing butt," says David Barton, who has gyms in New York City, Miami, Las Vegas, and Los Angeles. Standing with your feet shoulder-width apart, lower yourself to the ground as though sinking into an invisible chair. Once your thighs are parallel with the floor, squeeze your glutes together until you are upright again. Repeat 12 to 20 times.
The Cycle Climb. On your Spinning bike, get the most out of a standing climb by keeping your hands at the ends of the handlebars and your hips pulled all the way back above the saddle, says Stacey Griffith, an instructor at SoulCycle in New York City. "To really get the resistance, try not to move around too much."
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The Stair Hike. Office stairwells provide a high-incline hustle. "Go up ten flights, skipping every other step," suggests Teddy Bass, who trains Cameron Diaz. "Or lunge up onto the third step from the base of the stairs 15 to 20 times." Do three sets per leg.
Cute Curtsies. Step your leg behind you like you're bowing to the queen, and lower yourself until your knee is at a 90-degree angle. Do this 15 to 20 times on either side. "This targets that area right underneath the ass cheeks," says Bass.
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The Fresh-Air Run. Skip the treadmill for a run outdoors. "When the ground is moving under you, you're not working the muscles in back as much as those in front," says Barton. "On a track or the street, you push off the ground, squeezing and engaging those muscles."
The Covert Flex. Griffith reminds her clients, including Brooke Shields and Katie Lee, to work their glutes outside of class. "If you're riding in a taxi or sitting at your desk, flex your right cheek, then your left, and repeat," she says. "It's going to help give your butt a lift."