New research shows that people who are cheery are less likely to develop heart disease than those who are down in the dumps.
There's been speculation that people with a positive attitude have stronger hearts.
The Canadian scientists say their decade-long study, which is published in the European Heart Journal, has produced the first objective data to support the belief.
Psychiatrist Dr Karina Davidson, who is now working at Columbia University in New York, began the study more than 10 years ago.
Her team filmed interviews with more than 1700 people in Nova Scotia, Canada.
"We asked them about daily hassles, their daily routine, hypotheticals, what they do in certain situations and then the video tapes were coded for the amount of positive emotions or positive affect that was expressed," says Davidson.
The scientists tracked the people for a decade and at the end found those who had shown the most happiness and satisfaction were less likely to have had a heart attack.
"The very happiest people were quite protected from heart disease," says Davidson. "Those who showed moderate amount were somewhat protected and those who showed none at all were at increased risk."
She says the study revealed a positive attitude reduces the risk of heart disease by 22%.
Relaxed mind and body
Davidson says that could be because happy people tend to have healthier lifestyle habits, but the reasons could also be physiological.
"When someone is satisfied, content, feeling pleasure and enjoyment in the activity that they're doing, they have what is called a relaxation response. Their stress hormones go down, their blood pressure goes down, their heart rate slows."
The research team also hasn't ruled out that a common factor like genetics could be causing both the emotions and the heart disease.
Still, Davidson says for the sake of good health, people should do things they like every day.
"Ten to 15 minutes of something that you enjoy doing whether that's reading the newspaper, going for a walk, speaking to a friend," she says.
What if what you like to do and what relaxes you most is sitting in front of a DVD eating junk food?
"Both health care professionals and psychologists try and work with people to find the things that are not heart damaging," says Davidson. "So maybe you can sit in front of a TV with friends and not eat the high fat food or drink to excess."