Pain is the body's natural response to injury or any disease that damages the tissues.
It has 2 classifications - acute (short term) or chronic (long term).
It can occur for no apparent reason and be debilitating and wearing, not only physically but mentally. If you suffer from chronic pain it is easy to find yourself spiralling into depression.
Thanks to modern medicine, there are methods to help overcome pain without immediately opening the bathroom cabinet. Caution here - the causes of pain should always be investigated by a healthcare professional.