Happiness has been linked to improve health before
Being happy and staying positive may help ward off heart disease, a study suggests.
US researchers monitored the health of 1,700 people over 10 years, finding the most anxious and depressed were at the highest risk of the disease.
They could not categorically prove happiness was protective, but said people should try to enjoy themselves.
But experts suggested the findings may be of limited use as an individual's approach to life was often ingrained.
At the start of the study, which was published in the European Heart Journal, participants were assessed for emotions ranging from hostility and anxiousness to joy, enthusiasm and contentment.
They were given a rating on a five-point scale to score their level of positive emotions.
By the end of the analysis, some 145 had developed heart disease - fewer than one in 10.
But for each rise in the happiness scale there was a 22% lower risk of developing heart disease.
The team believes happier people may have better sleeping patterns, be less liable to suffer stress and be more able to move on from upsetting experiences - all of which can reduce physical strain on the body.
Lead researcher Dr Karina Davidson admitted more research was needed into the link, but said she would still recommend that people try to develop a more positive outlook.
She said all too often people just waited for their "two weeks of vacation to have fun" when instead they should seek enjoyment each day.
"If you enjoy reading novels, but never get around to it, commit to getting 15 minutes or so of reading in.
"If walking or listening to music improves you mood, get those activities in your schedule.
"Essentially spending a few minutes each day truly relaxed and enjoying yourself is certainly good for your mental health and may improve your physical health as well."
It is not the first study to suggest there is a link between happiness and health.
But Ellen Mason, of the British Heart Foundation, suggested such an association may be of limited value anyway.
"We know that improving your mood isn't always easy - so we don't know if it's possible to change our natural levels of positivity."
Cardiologist Iain Simpson, of the British Cardiovascular Society, added: "Things like reducing cholesterol and diabetes are more important when it comes to reducing heart disease.
"But at the end of the day it heart disease is still the biggest killer in the UK so anything you can do to help should not be ignored."