STARTING POSITION:
Stand straight and spread your feet at shoulder width apart. Place a box in front of you at your hip height. Place your right ankle on the box in front of you. Your knee and ankle should be in contact with the box and your knee should be around 90º.
MOVEMENT:
Slowly move your chest forward until you feel the stretch in your right piriformis muscle. Make sure you don't arch the back. Maintain the stretch during the required time and then do it with the other side.
TIPS: You should feel the stretch of the muscles but not pain.