"Our physical condition is determined very largely by our emotional condition, and our emotional life is profoundly regulated by our thought life."
Dr. Norman Vincent Peale, The Power of Positive Thinking
I'm currently reading Dr. Norman Vincent Peale's book - The Power of Positive Thinking - and I don't think I could have described better the relationship between one's thoughts, emotions and physical state of being. Most of us have accepted (even if in a peripheral way) that our emotions can wreak havoc on our bodies (say, for instance the way stress causes your back to tighten up), but we rarely make the connection between our thoughts and our emotions.
Have you ever listened in on your brain? Do you have any idea what it is saying to you on a day-to-day basis?