Although acute pain is mostly physical in nature, chronic pain has a significant psychological component. The treatment of chronic pain should include both medical and psychological interventions.

Chronic pain can be present because your body is not healing, because physical damage is ongoing (e.g. in arthritis, cancer etc) or without a clear physical cause. Emotional symptoms usually develop when medical treatment does not eliminate the pain and can increase the intensity of the pain. However, the presence of emotional factors does not mean that the pain is imaginary.

Psychological treatment helps you to learn how to predict and manage the pain cycle, how to use coping skills to minimize pain, and how to maximize active involvement in positive life experiences, despite the presence of chronic pain.

Source: http://www.wikipedia.com