Seal Jack

Start in a push-up position on your hands and knees, or on your feet if you want harder. Your hands stay planted, core tight. Jump or step your feet wide apart, then jump or step them back together. Your hands never leave the ground and your hips stay level. This keeps your upper body stable and the movement in your lower half. Control the landing; don't crash down. If you're taking this fast, the impact becomes the whole point — you're training your legs to handle explosive changes of direction.