You could read this list to yourself 3-4 times a day for a week or more to help reprogram your mind to think more positively. (Taken from the book, What to Say When You Talk to Yourself by Shad Helmstetter)
*I am in control of my own thinking & I think only those thoughts which create & fulfill the best in me.
*My mind is constantly in tune with the positive. It is bright, cheerful, enthusiastic, & full of good, positive thoughts & ideas.
*I am able to relax easily and comfortably in my body & in my mind. I am calm, confident, & self-assured.
*My mind is orderly & well-organized. I consciously choose what I think & I choose those thoughts which are the most positive & beneficial for me.
*All of my thoughts create healthiness within me.
*My mind dwells only on those thoughts which create more harmony, balance, & well-being within me & in the world around me.
*I automatically, & always, think in a decisive & determined way.
*I am full of resolution & the absolute assurance of the best possible outcome in everything that I do.
*I choose to look at the world around me in the bright, healthy light of optimism & self-assurance.
*I do only those things which are best for me. I create the best within myself, I attract the best in others, & I find the best in the world around me.
*I keep my mind focused on healthy, positive, constructive, & productive thoughts.
*I control the thoughts I choose.