In medicine, we study the natural history of disease.  After we understand the natural course of a disease, we can figure out if treatments are worthwhile.  Many disorders are self-limited; they go away on their own if you ignore them and let them run their course. 

Often it’s hard to know whether a medication has a positive effect when the natural history of a disease is spontaneous recovery.  Many medications only shorten the course of a disease that would go away on its own.

After studying the natural history of negative thinking for more than fifty years, I know negative thinking doesn’t get better on its own.  Spontaneous recovery isn’t part of its natural history; it only becomes worse when left untreated.  Negative thoughts always generate more negative thoughts.  The more negative thoughts you think, the faster they come, and the more rapidly they accumulate into a mountain of toxic waste.  Once they are in your mind, they don’t go away until you do something about them.

This natural history means that the only appropriate response to a negative thought is positive action.  Negative thoughts are a call to positive action.  If positive action isn’t your immediate and unequivocal response, you will sink in a quagmire of negativity.

Positive action is the pivot on which your life turns.  Negativity will never expand massively into your life if you take positive action.  Whenever a negative thought enters your mind, it’s an automatic signal that tells you to immediately take positive action to eliminate it.

Excerpt from :

Zero Tolerance To Negative Thinking : Good-by Depression - Hello Positive Mind

David J Abbott M.D.