HOW: Start in a seated position with your feet flat on the ground. From here, push into the ground with your toes lifting your heels up, followed by returning to the starting position and lifting your toes off the ground. Alternate bringing your heels and toes off of the ground for the prescribed amount of reps.
FEEL: You should feel your calf muscles working and a stretch in your ankles.
COMPENSATION: Keep your ankles underneath your knees.