Achieving happiness may be more important to your health than you think.
In a 2008 review of studies on happiness and longevity, Dutch sociologist Ruut Veenhoven found that happiness appears to protect against illness.
In 19 research projects involving populations chosen independently of their health status, ratings of mood, happiness, and life satisfaction at the beginning of a study had a large and positive impact on the chance a person was alive at the end of the follow-up period.
The most satisfied people gained an extra 7.5 to 10 years of life
Source: Veenhoven, harvard.edu, 2008