Stand with your feet together and your arms out in front of your chest for stability. Take a large step back with your right foot.
Lower your hips until your left thigh (front leg) is parallel to the floor, with your left knee positioned directly over your ankle. Your right knee should be at a 90-degree angle, pointing toward the floor with the heel lifted.
Swing your right leg forward up toward your chest, pushing off the ground with your left foot into a skip. As your knee pops up, your right hand should swing back and your left hand forward.
Land softly back in a lunge, and repeat with the same leg for the full 40 seconds.
Once the 40 seconds is up, rest and complete the move with the left leg.