Press behind-the-neck with barbell seated on a stability ball

Press the load overhead without over-arching the lower back. Lower under control to the point where the shoulders and torso remain stable. Use a steady tempo: control the return phase in particular and avoid relying on momentum. Exhale through the hardest part and inhale as you recover the starting position.

Check that the movement stays stable in both directions and that the torso is not compensating. The goal is controlled loading of shoulders; match resistance and range to a intermediate level and never force a painful repetition. On unstable surfaces, master the position with light resistance first; stability should limit difficulty before load does.