Stand in a split stance, one foot forward and one back, with the opposite arm raised overhead. Jump and switch your legs in mid-air, landing softly with the other foot in front, while your arms swap positions like a sprinter's - front arm sweeping back, back arm swinging up. Keep the stance long and the rhythm springy. Opposite arm, opposite leg, every time - once the coordination clicks, it runs itself.

Works: quads, glutes, calves, shoulders

Breathing: Steady and rhythmic, exhaling with each switch.

Common Mistakes: Landing stiff-legged with straight knees, letting the stance shrink until the feet nearly meet, and moving the same-side arm and leg together.

Make Easier: Step-switch the feet instead of jumping while keeping the arm swings, shorten the stance, or slow the rhythm down.

Make Harder: Sink deeper into each landing and pick up the pace, or move on to Jumping Lunges to turn every switch into a full lunge.