Sure, some classes incorporate strength work. But boxing itself is an excellent cardio workout that gets your heart rate up and works your whole body. "While I admit I'm biased, I believe it is probably the best cardio-driven training you can do," Kendall said. "You're challenging the body with short bursts of powerful strength while punching, combined with the consistent need to stay moving and light on your feet and pushing your body's endurance to new levels."