New York City-based SLT (which stands for strengthen, lengthen and tone) sets up shop in centrally located Rittenhouse, making it easy to drop in for stress-relieving classes even on a lunch break. Megaformer machines (raised weighted benches with a sliding platform) form the center of these core-focused, low-impact workouts that combine cardio and Pilates in just under an hour. Single drop-ins $32, combo packs $75-$520. Private sessions available. Classes offered daily. Reserve online.