According to Daniel G. Amen, MD, author of the classic book Making a Good Brain Great, every thought releases brain chemicals. Positive, happy, hopeful, optimistic, and joyful thoughts produce yummy chemicals that create a sense of well-being and help your brain function at peak capacity; unhappy, miserable, negative, and dark thoughts have the opposite effect, effectively slowing down your brain and even creating depression. If you tend to focus on what can go wrong, or what is wrong, or how unhappy you are, or how someone hurt you, these negative thoughts can dim your brain’s capacity to function. They sap the brain of its positive forcefulness. Dr. Amen suggests writing out negative thoughts to dispel their power over your brain.