Pain, particularly chronic pain, is much more complex than that. Pain usually starts with some kind of physical injury. This pain is called acute pain. It serves as a warning signal. But the kind of pain that most people worry about is chronic pain.
Chronic pain is by definition, pain which persists beyond the usual healing time.
Most acute diseases or injuries heal in 2 to 6 weeks. Chronic pain occurs when things have not healed and complications occur. In addition to the initial injury, other problems arise including muscle tension, changes in circulation, postural imbalances and changes in the functioning of the central nervous system. The exact causes of chronic pain are not fully understood. Pain is also a subjective experience.