Lower the carriage of a cable machine so it's about chest height, and attach a D-handle to the pulley. Adjust the weight so it's at 10 pounds. If this is too heavy or too light, feel free to change the weight.
Standing with the left side of your body closest to the machine, grab the handle with both hands and take two or three steps out so there's tension on the cable. Hold your hands at your sternum, and make sure your body is square. If you feel like you're getting pulled to the left, this is an indicator that you should lighten the weight.
On an exhale, press the cable straight out in front of your body. Be sure not to rotate toward the machine. Hold for two seconds before returning to the starting position.