Stand with your feet touching. Hold your hands comfortably in front of your chest to help you stay balanced and bend your knees, lowering your hips deeply, bringing your thighs parallel with the floor if you can. Be sure to keep weight back in your heels.
Then rise back up, straightening the legs completely, squeezing the glutes at the top of the movement to get the most out of the exercise.
Rise back to standing and hop your legs out so you're in a wider squat.
Lower hips, keeping your weight in the back of your heels, then raise back up and hop back to a narrow squat.
Continue alternating between these two squats for 45 seconds, then rest for 15 seconds.