Shoulder flexion sitting - long lever with weight

Sit upright in a chair with your hands relaxed by your sides.
Hold a weight in your weaker arm.
Leading with your thumb, slowly lift your weaker arm up, keeping the elbow straight.
Ensure your back and neck muscles remain relaxed as you move your arm.
Hold this position before returning your arm back down to your side.
Do not hunch your shoulder on the descent.