"The brain is like a muscle. The more you use a muscle, the thicker it gets. If you stop using it, then it atrophy's and gets smaller. Further, anytime you change your way of thinking, many connections that correspond to your old way dissolve and those that identify with your new mode of thinking begin to grow.

 

Maybe you've always been someone who complains about things or worries about things. Inevitably, you will have built up brain maps that process your negative thoughts and emotions. But then you decide that you're going to look at things differently. You've decided to think positively and practice gratitude. You'll begin growing new maps that process your new way of thinking and the complaint or worry based maps will naturally begin to shrink. In a surprisingly short period of

time (many studies have shown it to be around 21 days), your new positive map will become larger than the negative one.  At the neurological level, positive thinking and gratitude become a habit. These new ways are now wired into your brain and you really are a different person.  All you need to do is make the effort to change your mind. Your brain responds to the revisions and in time as it develops new maps you don't need to make as much effort anymore. The new behavior is wired and has become routine."

                

                  David Hamilton, How Your Mind Can Heal Your Body

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