Many of the rehab posts I put up are focused on the lower body due to the fact that TKD is a kicking art and this area is pertinent to many of us. However in martial arts our shoulders and in particular the rotator cuff can take a battering with repetitive movements, the dynamic nature of blocking against an opponent or trauma during sparring. As the shoulder joint is not load bearing, when its injured we probably don't experience the same constant discomfort and pain that we might with our hips. Due to this we can tend to ignore these pains and discomfort when training and find ways around the limitations it brings or just stop doing certain conditioning exercises altogether due to the pain and instability.
Ignoring this issue is a mistake as once a problem becomes chronic getting rid of it can be very difficult and will limit your training and performance abilities.
Take a look at the attached video for some rehabilitation ideas to keep the shoulder joint healthy and working: