When something is wrong or the body is in some way injured, the nerves send millions of small messages to the brain to let it know what is happening. The brain then makes the body feel pain in the area the message came from.
When you are aware of pain it can leave you in discomfort, especially if the painful area cannot be treated. For the body natural painkillers can work to minimise the pain or inflammation, allowing people to continue with their daily lives without extreme discomfort.