The highly emerging field of positive psychology states that Optimism not only has a good impact on mental health but also on physical health.
Optimists fall sick less often, heal faster and live longer than pessimists.
Their positive outlook on life strengthens the immune system (Body's defence against illnesses) and body's ability to handle stress.
An optimist does not blame himself /herself when something untoward or bad happens, they view those events in life as a result of something outside of themselves.
They generally have a bright future owing to this nature and a better ability to handle situations.
They say When sometimes you are in a dark place and you think you have been buried, you have actually been planted.