Is the secret to happiness a warm puppy? A good marriage? A rewarding career? Or something else entirely?
Happiness means different things to different people, but a growing body of research suggests keeping a smile on your face may help add years to your life by lowering the risk for cardiovascular disease and death from all causes.
Not feeling it? Health experts say there are daily habits that might just make a difference. Here are five:
Keep it moving
Granted, the words "physical exercise" don't always make people smile. They might even elicit groans. But studies show people who get up and move more — even if it's in short bursts a few minutes each day — feel happier and live longer.
"When you engage in physical activity, you see benefit in the form of emotional well-being," said Rosalba Hernández, a member of the American Heart Association's Lifestyle and EPI Behavioral Change for Improving Health Factors committee. Hernández is an associate professor and associate dean for equity and inclusion at the University of Illinois Chicago's College of Nursing.
And the better you feel, the more likely you are to stay active, she said. "It's a cyclical relationship."
When the body engages in exercise, the brain releases dopamine, serotonin, endorphins and endocannabinoids, which relieve stress, improve mood and help you sleep better. Research shows exercising in groups also can help social bonding and increase the motivation to move more, further fueling good feelings.
But if a trip to the gym doesn't make you smile, don't worry, said Matt Whited, a clinical health psychologist and associate professor of psychology at East Carolina University in Greenville, North Carolina.
"Physical activity can look like whatever works for each person and their lifestyle," he said. "Walking is a fantastic option, but anything that keeps your interest and feels good will work."
The AHA recommends adults get 150 minutes of moderate intensity aerobic physical activity or at least 75 minutes of vigorous activity each week.
Whether moving or sitting perfectly still, being mindful also can contribute to less stress and a more positive outlook, Hernández said.
Being mindful is about letting go of the stress from past or future events, she said. "Being in the present moment without judgment allows you to interrupt harmful ruminations" and reduce stress hormones. "Take the time to let your brain relax."
Whited said many people assume mindfulness means meditation, but, like exercise, being mindful can look different to different people. He thinks of it as a way to clear his head and finds even taking the dog for a five-minute walk can accomplish this.
"Just focus on that moment you are in and leave the last one behind," he said. "Don't be checking your phone or texting."
Create a happy space
"There's so much research showing our environment is a key factor in our health," Whited said. "Do a little something for your environment each day that will create and sustain happiness."
That can be as simple as decluttering or cleaning a workspace, he said. Or it might be more involved, like setting boundaries to prevent toxic people from bringing stress into the home or work environment.
In an even broader fashion, it can mean getting involved in local government decisions to improve the community you live in, Whited said. "Decide who to vote for. Write letters and attend town halls."
"Sometimes it's big, sometimes it's little stuff," he said. "You can't dismiss the little stuff."
Good things happen every day, and it helps to take the time to recognize them, Hernández said. "Instead of just focusing on what you don't have, focus on what you do have."
She recommends making a short list of things to be grateful for each day or writing a letter of gratitude to someone and then reading it to them. "Well-being goes up for both the recipient and the writer," she said.
Eat more plants
Something Whited does for himself every day is to make sure he's eating enough fruits and vegetables, an important component of good cardiovascular health. Research shows people who eat more than three portions of fruits and vegetables per day are happier than those who don't.
Whited, who likes to snack on carrot sticks, said many people forego fruits and vegetables as snacks because "they worry they won't fill them up."
But he finds it easy to grab an apple or a couple of carrots after a long workday, when he wants to nibble on something before dinner. "I ask myself, 'Did I live a good day today? Did I eat some plants?'" he said. "The American diet is terrible, and the stuff we eat when we are busy is not plants. We should all eat more plants."