Start with your feet shoulder-width apart, toes pointed straight forward. Step out with your right foot as wide as comfortable. Squat down and drive through the right heel, while keeping the left leg straight. Keep your back neutral.
Keep soles of the feet on the ground and toes pointed straight forward. Make sure your right knee tracks over your right foot, and does not collapse inward.
Powerfully “punch” your right heel into the floor to push yourself back to the full standing start position. Repeat for repetitions before switching legs, or alternate sides each rep.
Form note: Make sure you’re sitting down, as in a standard squat rather than hinging at the hips. Also, plant your foot firmly on the ground at full extension, and keep your toes pointed forward throughout the whole move.