For every inch your head moves forward of your upper back the strain on your neck increases exponentially! Thus, it is essential to try and maintain a more erect posture when working at a desk, driving a car, or performing arm activities (such as carrying things). Your body's musculature serves two functions – to produce movement and to control or guide that movement. The large, superficial muscles produce movement and are usually very active and easy to train. The deeper muscles that guide movements are important for preventing injury and they often become weak when you are in pain and thus require specific therapeutic exercises to activate and train them.