Like most aspects of life in Manhattan, New Yorkers don't take working out with a grain of salt. We go all out when it comes to fitness, which explains the abundance of boutique studios thriving in the Big Apple right now. In honor of a whole new year of wellness on the horizon, we're spotlighting the hottest classes in N.Y.C., from heated Vinyasa yoga to treadmill-based endurance workouts. These classes, which are all the rage among gym rats, have one thing in common: They are in high demand by endorphin-loving fitness fanatics. Behold, our favorite New York City workouts. Bring on the sweat.