Positive psychological well-being, especially optimism, protects against the incidence, and somewhat against the progression, of cardiovascular disease through a broad array of mechanisms, according to this extensive literature review.
While low levels of negative emotion or high levels of cardiorespiratory fitness are predictors of long-term survival in men and women, being both fit and not unhappy provides a strong combined effect, reducing premature death by 63 percent, according to this study.