W-Raise

Most people bounce the weights up and call it a shoulder exercise; the eccentric — the lowering — is what actually builds your rear delts and upper back. Stand tall holding light dumbbells at your sides. Your elbows bend to roughly 90 degrees, and you raise them up and out to the sides until they're about shoulder height. Pause and squeeze your shoulder blades together. Then lower under control, taking a full 2 to 3 seconds on the way down. Don't let them drop. Light weight and controlled tempo beat heavy weight and swinging.