That was the best answer I could give, and it was not good enough for me, so I have done some extensive searching for the answer or at least what I feel is the answer. Ph.D, author of Anatomy of the Spirit , The Seven Stages of Power and Healing , is a Medical Intuit who helps physicians diagnose patients by reading their energy. Her book has nothing to do with Reiki, and everything to do with the body's energy and how the energy of the body can manifest into sickness and disease. I put Dr. Myss' thoughts on energy with my thoughts on Reiki and these are my conclusions. The more leaks we have, the less healthy we are.
Positive thoughts create healthy cells, negative thoughts create unhealthy cells.
This being the case, if we consistently live with fearful or bitter attitudes, we are setting ourselves up to become ill. Well, of course we all have negative thoughts, and not all negative thoughts will produce illness. To create disease, negative emotions have to be dominant, and what accelerates the process is knowing the negative thought to be toxic but giving it permission to thrive in your consciousness anyway. For instance, you may know you need to forgive someone, yet you decide that remaining angry gives you more power. Remaining obsessively angry makes you more likely to develop a disease because the energy consequence of a negative obsession is powerlessness.