The next time you're at the gym, elevate your workout with box jumps. A popular exercise among athletes and in CrossFit workouts, box jumps test speed and agility while also increasing your heart rate. To do this plyometric exercise, all you need is a box (solid or padded) or an elevated platform. Depending on your fitness level and goals, use a single box to improve your agility or stagger boxes for obstacle-testing efficiency. Before you get jumping, keep these tips in mind: