TOXIC EMOTIONS AND THINKING
Dr. Carolyn Leaf has studied the human brain since 1981 and wrote a book about the effects of toxic thoughts. Below is a list from her book of common toxic thoughts:
• "could-have", "would-have", "should-have" statements
• "if only" statements• replaying situations that pained you or that haven't even occurred yet• creating the unpredictable future• making comments like "nothing ever goes right for me"; "everything I touch fails"; "I always mess up"• Are you at cross-purposes with yourself - going through the motions, but not really committed to the goal, saying one thing but meaning another? How honest are you with yourself?• How distorted is your thinking? Are you forming a personal identity around for example, a disease? Do you speak about "my arthritis", "my multiple sclerosis", "my heart problem"? 
On a surprising note, Dr. Aaron Beck believed that toxic emotions arise from three negative and incorrect beliefs that people commonly think:
1. I must do well2. You must treat me well3. The world must be easy 
Dr. Marion Diamond, another groundbreaking brain researcher, describes memory networks. In effect, these networks create "copies" of your "thought life" along with the emotions that the chemicals coursing through your bloodstream literally carry around your whole body like an information highway. Information molecules are then able to cause changes at the cellular level, actually restructuring the cell's makeup on the outside and the DNA on the inside. This is how diseases are able to take hold in the body.  The toxic waste that builds up actually distorts your memories!
The list of diseases and chronic disorders caused by toxic thoughts and emotions is quite long and includes all the major maladies of the day.
Unmaking or unlearning old belief patterns is extraordinarily difficult by consciously attempting to unmake them or change them.
But it is possible to change deep-seated belief patterns easily and effortlessly. This is done by the introduction of a few new seed thoughts. These seed thoughts have the unique and invaluable characteristic of systematically and effortlessly expanding the conscious boundaries of the individual’s mind. Each of these seed thoughts has the result of unmaking past belief patterns that keep our lives from unfolding in a healthy and harmonious way. Each of these seed thoughts, correctly practiced, causes the entire range of the personality to become aligned with the most basic force in the Universe.
"The Ascension Attitudes are designed to clear out past beliefs and behavior patterns that inhibit full mental and physical functioning. By effortlessly introducing these seed thoughts at a deep and refined level of thinking, the entire structure of the mental framework gradually and gracefully transforms to reflect Reality." 
 Leaf, C. PhD, 2007. Who Switched Off My Brain; controlling toxic thoughts and emotions.
 Beck, A. et al., 1979. "Cognitive Therapy and Depression." New York: Gilford Press.
 Diamond, M. and Hopson, J. 1999. "Magic Trees of the Mind: How to nurture your child’s intelligence, creativity and healthy emotions from birth through adolescence." England: Plume. MSI, Ascension