HOW: Get set up standing and then position your feet together, but one foot slightly in front of the other. With the foot that is further behind, the big toe on that foot should be lined up in the middle of the opposite foot. While keeping your heels flat on the ground, bend both knees forward so that you feel a deep calf stretch more on the foot that is further back. Hold this position.
FEEL: You should feel a deep calf stretch above your Achilles tendon. Keep your knees together and guide them forward to help perform the stretch correctly. You shouldn't feel sharp pinching pain in the front of your ankles, if you do modify your set up.
COMPENSATION: Your knees should progress directly forward, do not let them cave in or not and make your arch excessively collapse. Follow the video for tips.