A university study has shown older people who take a positive outlook are likely to have better immune systems and may live longer.
When American pop star Bobby McFerrin sang Don't Worry, Be Happy, he wasn't just offering the world a catchy tune.
It seems he was also providing sound health advice.
A University of Queensland study has discovered a positive attitude can improve your immune system and may even help you live longer.
Researchers at the university's School of Psychology discovered older people who focused on positive information were more likely to be happier, and healthier too.
"Despite the fact that people often think of late life as a period of doom and gloom, older people are often more positive than younger people," lead researcher Elise Kalokerinos said.
"Our research suggests that this focus on the positive may help older people protect their declining health."
The study over two years involved 50 people aged from 65 to 90.
Participants were shown a series of positive and negative photos, which they were later asked to recall, and their immune function was also measured through a series of blood tests.
The research, which has been published in quarterly magazine Psychology and Ageing, showed participants who remembered more positive than negative images showed better immune functioning up to two years later.
"By selectively remembering the positive, older adults seem to boost their immune functioning just when they need it the most," Dr Kalokerinos said.
"We already know that happiness provides a range of health benefits, and this research shows that focusing on positive information may have the same effect for older people.
"A person who focuses on positive information over negative information may be better able to cope with stressful situations, may take a more positive long-term outlook on life, and may maintain positive social interactions, thus reaping the immune benefits."