The pectoral fly/rear deltoid exercise is a combination movement that targets both the chest muscles (pectoralis major) and the rear deltoids (posterior deltoids). This exercise can be performed using a cable machine or dumbbells. To perform the pectoral fly/rear deltoid exercise using a cable machine: 1. Adjust the pulleys on the cable machine to a high position. 2. Stand in the center of the machine and grab the handles with an overhand grip. 3. Step forward slightly and lean forward at the hips, keeping a slight bend in your elbows. 4. Keeping your arms slightly bent, bring your hands together in front of you in a flying motion, squeezing your chest muscles. 5. Slowly return to the starting position, keeping tension on the cables. 6. Next, open your arms out to the sides in a reverse fly motion, squeezing your rear deltoids. 7. Slowly return to the starting position and repeat the movement for the desired number of reps.