Mayo Clinic Proceedings study: People who scored high on optimism had a 50% lower risk of early death than those who were more pessimistic. (O’Brien, Mary, MD. Successful Aging. CA: Biomed General. 2007, p 102)

Reports on studies: an optimistic attitude can actually help to prevent you from getting sick. (Hafen, Brent Q., et al. Mind/Body Health. MA: Simon & Schuster, 1996, pp 510-512)