What it is: A combination of barre, yoga, Pilates, and ballet set to pop music that is great for burning calories and improving posture, flexibility, strength, and muscle tone.

Why it became popular: Created by former professional ballerina Jennifer Williams a few years ago, Pop Physique isn't necessarily for everyone. As you'd probably expect, it looks a lot like ballet when you're doing it (partly because you're not allowed to wear any shoes during classes). But it reportedly burns upwards of 500 calories per session because of all the different movements that you're forced to attempt while doing Pop Physique. So people feel the burn while they're doing it, but they also get quick results because of it. And really, isn't that what you're looking for when you work out?