After analysing health data of 8000 people spanning over three decades, they found those who initially described their health as "very poor" were 3.3 times more likely to have died than those who had felt "very well".

"Our results indicate that people who rate their state of health as excellent have attributes that improve and sustain their health," says researcher David Faeh.

"These might include a positive attitude, an optimistic outlook and a fundamental level of satisfaction with one's own life," he added.