our bodies are designed to be entirely self healing and when that process fails it is usually due to a decision we are making that is stopping the healing process from succeeding. if we are fully unified internally - connecting all our facets as one, for example the mind and body as one - then there is no problem, however, most of us are not that way and so our mental aspects which are usually designated as 'decision maker' must learn now to listen to the other voices inside for us to have balance.
'yoga' literally translates to 'union' for this reason. ;)