Seth -- A long period of inner depression does not just come upon you

Your beliefs generate emotion. It is somewhat fashionable to place feelings above conscious thoughts, the idea being that emotions are more basic and natural than conscious reasoning is. The two actually go together but your conscious thinking largely determines your emotions, and not the other way around. Your beliefs generate the appropriate emotion that is implied. A long period of inner depression does not just come upon you. Your emotions do not betray you. Instead, over a period of time you have been consciously entertaining negative beliefs that then generated the strong feelings of despondency.

Here the belief itself will generate the negative emotions that will, indeed, bring about a physical or emotional illness. The imagination will follow, painting dire mental pictures of a particular condition. Before long physical data bears out the negative belief; negative in that it is far less desirable than a concept of health.

—Seth, The Nature of Personal Reality; Part One: Chapter 4: Session 620, October 11, 1972