Your mind is like a one way street in which the direction of the traffic is always changing, and focus determines what the direction will be.  If you let depression determine the direction, you travel to a depressing destination.  If you chose a positive direction, you head for a positive destination.

Negative thoughts never travel alone.  They always have a negative entourage traveling with them.  It's impossible to think only one negative thought.  The first negative thought brings a cascade of rude negative companions pushing and shoving their way into your consciousness.  It's suddenly rush hour in your mind, and all of your mental traffic heads in a negative direction.

The good news is that when you focus on positive things, the traffic on the one way street instantly heads in a positive direction.  That is why focus is so important.  You must have a positive focus, or you will suffer negative consequences.  The traffic is going to head one way or the other, and if you're smart, you will choose a positive direction.

When you choose a positive direction, you turn on a positive operating system.  It's as if you had flipped a switch in your mind, and now a positive operating system assumes control.  You now have a positive self-image and positive self-esteem.  A positive operating system interprets events in a positive manner giving them a positive meaning.  It looks for the good in everyone and everything, and it has positive expectations.  It has a positive spirituality based on love.  It gives you real power over your biggest problems, and it takes you to a positive destination.  There is no limit to how good your life can become when a positive operating system controls your mind.

Excerpt from :

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

David J Abbott M.D.