When you train your shoulders, you often only really develop the large muscles while the smaller supporting muscles like the rotator cuff do not get strengthened, this can lead to an imbalance that can cause some pretty serious shoulder discomfort.

I have also found that the supporting muscles in general even if you are not training at all can for some reason be under developed and so the exercises in this video may be useful to just about anyone with an annoyingly sore shoulder.

I hope these tips help you out!