People who are happy and have a positive outlook live longer, according to scientists.
It is now hoped the findings from the University College of London will further promote 'positive well-being' as a remedy for stress and ill health.
Participants involved in the study were asked to rate their feelings of happiness or anxiety four times over the course of a day.
The number of deaths were then recorded over a five-year period.
After taking into account age, gender, depression, certain diseases and health-related behaviours scientists found those who reported feeling happiest had a 35 per cent reduced risk of dying early compared with those who reported feeling least happy.
Lead researcher Professor Andrew Steptoe said: 'The present findings provide further reason to target the positive well-being of older people.'
The long-term study, published in the Proceedings of the National Academy of Sciences, backs previous scientific claims that a 'glass half full' approach can have various health benefits.
In March scientists from the University of Illinois found positive moods reduced stress-related hormones and strengthened the immune system.
In a review of 160 animal and human studies Prof Ed Diener and his team concluded that happiness 'contributes to both longevity and better health among healthy populations.'
Meanwhile anxiety, depression, and pessimism were linked to higher rates of disease and a shorter lifespan.
In recent years positive psychology has received growing interest and in 2006 cognitive-behavioral therapy (CBT) - a form of psychotherapy that promotes happiness - was made available to NHS patients in a bid to tackle the £17 billion cost of depression and anxiety on the UK economy.
Despite the recent findings Professor Steptoe said that there is still no proof feeling happier extends life-span and instead stressed the importance of emotional well-being among older people.