Dancing at 305 Fitness—a hugely popular dance-cardio studio in New York City and Washington, D.C., complete with live deejays and party lights—isn't just about shaking what you've got. It's about mixing high-intensity cardio and strength moves for a fun, effective workout. This routine focuses on tightening and toning your butt while working your entire body. Plus! See the step-by-step guide to each move.

Your trainer: Sadie Kurzban, a Brown University graduate who founded 305 Fitness when she was just 23.

Do this: Three times a week to your favorite upbeat, high-tempo playlist. The first few times through you'll build muscle memory. Don't worry if it feels awkward; that's normal. You're still getting a great workout!