Most people understand how emotional stress can contribute or cause certain types of health problems. Everyone knows when the chemistry of the body is not normal, you can develop health problems, however the majority of people do not understand how and why many health problems can come about from physical cause.
An example of how a problem can come about from something physical would behaving a pebble in your shoe. You would feel pain from the pebble. The pain would not be from something chemical or emotional. If you were in pain long enough this could lead to emotional stress and could perhaps even throw off your chemistry in the area, but the cause of the problem would actually be something physical. The reason a person feels pain when there is a pebble in the shoe is because the pebble puts pressure on a nerve of pain. If there was no nerve of pain in your foot you would not feel the pebble.
A common cause of pain that people suffer with is, in fact, pressure on a local nerve. An interesting fact is that only 10% of the nerves in the body are related to pain. 90% of the nerves in the body control your function.
For example, you can see if the nerves of sight are functioning properly; you can hear only because the nerves of hearing are functioning properly. You can move your arm because the nerves that control the muscles of your arm are functioning and you can breathe and digest if the nerves related to these areas are functioning properly. Put pressure on nerves of function and you feel no pain, you simply do not function properly.
When you remove a pebble from your shoe, pain disappears because pressure or irritation to the nerve has been physically removed. If there is pressure on nerves in the neck causing head or neck pain, when that pressure is relieved these problems will clear up. If there is pressure on a nerve inhibiting normal function, when that pressure is removed, normal function is once again restored.
This explains why some people have gone to a chiropractor for back pain and then recovered from a different problem altogether. As they were treated to remove pressure from the nerves that were giving them pain, their digestive or breathing problems improved as well.