Physical conditions, such as changes in posture, lessening of strength and stamina, difficulty moving, and weight gain all contribute to compensating. Compensating for pain causes the body to change. Pain affects the endocrine, digestive, respiratory, urinary, integumentary, muscular, nervous, skeletal, lymphatic, reproductive, and cardiovascular systems. Chronic pain can cause many of the body's chemicals to be out of normal ranges. This can lead to a variety of disorders. The chemical changes that occur breakdown the immune system causing illnesses.