Cable Lying Fly

Attach the handles to the cables and lie flat on a bench with your feet flat on the ground.

Hold the handles with your palms facing each other and your arms extended straight above your chest.

Keeping a slight bend in your elbows, lower your arms out to the sides in a wide arc until you feel a stretch in your chest.

Pause for a moment, then squeeze your chest muscles to bring your arms back to the starting position.

Repeat for the desired number of repetitions.

Recruiting larger muscle groups to "help" move the weight instead of isolating Pectorals — swinging momentum or shifting the torso takes tension off the muscle this exercise is meant to train.

Locking out too fast or letting the elbows drift outward under load — controlling the eccentric (lowering) phase is where most of the muscle-building stimulus happens.

Standing too close to or too far from the pulley, which changes the resistance curve and can take tension off the target muscle at the top or bottom of the rep.

Skipping a warm-up set at lighter load/intensity — even "beginner" exercises benefit from a rehearsal set to groove the movement pattern before working sets.