"Basically, more than any other class, it really isolates the muscles, so you feel like it's actually shaping your body," explains Beth Bernstein, one of Reyna's students. "And it's really fun. That's important because that's what keeps me coming back."

In a dance studio, Reyna would normally spend time teaching the moves slowly, concentrating on proper form, but her gym class is less technical. "I can't break down everything because it is a big studio, and [explaining] takes too much away from people wanting to get a workout." Surprisingly, though you have to watch the teacher closely, it's easy for a beginner to catch on to the spirit of her movements and enjoy their physical benefits ‑- even if you won't be ready for the stage any time soon. After stretching and warming up with the basics, Reyna builds the class up to a 20-minute block of fast-paced, nonstop shimmying and shaking, set to motivating drum music. It never reaches the sweaty, heart-pumping level of, say, kickboxing or spinning, but you will start to feel every muscle doing its job during this exhilarating portion.

The mental challenge of learning all these new ways of using your body prevents boredom and fatigue. And once you wrap your inexperienced hips in a scarf adorned with coins and beads, even the most amateur twists and wiggles look enticing and produce a satisfying jingle. Need we mention the confidence-boosting rewards of learning and performing something that looks so sexy? It's not like you've ever been dying to show off your mastery of sit-ups in the bedroom.