Explanation:

1. Place your feet shoulder-width apart;
2. Make fists with your hands and keep your arms flexed under your chin;
3. Extend your right arm forward as far as possible and bring it back;
4. Move back to the starting position;
5. Next, extend your left arm forward as far as possible and bring it back;
6. Move back to the starting position;
7. Bend through your knees (make a squat) with your buttocks back and chest out;
8. Move back to the starting position;
9. Repeat this movement at a fast pace.