One of the most common injuries that people will get from working out is a shoulder injury. The shoulders come into play in virtually every single upper body exercise you do, and they also get worked with some lower body exercises as well such as squats where the barbell is held across your back. So if you get a shoulder injury it can really hamper your workouts for the entire body.
One of the root causes for shoulder injuries is a muscle imbalance between the front delts and the rear delts. Generally the front delts get much more muscle stimulation and are over developed compared to the rear delts. So to counter this you should include more rear delt work in your training such as the rubber band rear delt flyes.