It turns out, giving thanks is good for your health.

A growing body of research suggests that maintaining an attitude of gratitude can improve psychological, emotional" target="_blank" title="a.易动感情的；情感的">emotional and physical well-being.

Adults who frequently feel grateful have more energy, more optimism, more social connections and more happiness than those who do not, according to studies conducted over the past decade. They're also less likely to be depressed, envious, greedy or alcoholics. They earn more money, sleep more soundly, exercise more regularly and have greater resistance to viral infections.

Now, researchers are finding that gratitude brings similar benefits in children and adolescents. Kids who feel and act grateful tend to be less materialistic, get better grades, set higher goals, complain of fewer headaches and stomach aches and feel more satisfied with their friends, families and schools than those who don't, studies show.

'A lot of these findings are things we learned in kindergarten or our grandmothers told us, but we now have scientific evidence to prove them,' says Jeffrey J. Froh, an assistant professor of psychology at Hofstra University in Hempstead, N.Y., who has conducted much of the research with children.

'The key is not to leave it on the Thanksgiving table,' says Robert Emmons, a professor of psychology at the University of California-Davis and a pioneer in gratituderesearch. And, he notes, 'with the realization that one has benefited comes the awareness of the need to reciprocate.'

It's possible, of course, to over-do expressions of gratitude, particularly if you try to show it with a gift. 'Thanking someone in such a way that is disproportionate to the relationship -- say, a student giving her teacher an iPod -- will create resentment, guilt, anger and a sense of obligation,' says Dr. Froh.

Gratitude can also be misused to exert control over the receiver and enforceloyalty. Dr. Froh says you can avoid this by being empathic toward the person you are thanking -- and by honestly assessing your motivations.

In an upcoming paper in the Journal of Happiness Studies, Dr. Froh and colleagues surveyed 1,035 high-school students and found that the most grateful had more friends and higher GPAs, while the most materialistic had lower grades, higher levels of envy and less satisfaction with life. 'One of the best cures for materialism is to make somebody grateful for what they have,' says Dr. Froh.

Much of the research on gratitude has looked at associations, not cause-and-effect relationships; it's possible that people who are happy, healthy and successful simply have more to be grateful for. But in a landmark study in the Journal of Personality and Social Psychology in 2003, Dr. Emmons and University of Miami psychologist Michael McCullough showed that counting blessings can actually make people feel better.

As simple as it sounds, gratitude is actually a demanding, complexemotion that requires 'self-reflection, the ability to admit that one is dependent upon the help of others, and the humility to realize one's own limitations,' Dr. Emmons says.

Being grateful also forces people to overcome what psychologists call the 'negativity bias' -- the innate tendency to dwell on problems, annoyances and injustices rather than upbeat events. Focusing on blessings can help ward off depression and build resilience in times of stress, grief or disasters, according to studies of people impacted by the Sept. 11 terror attacks and Hurricane Katrina.

Can people learn to look on the bright side, want what they have and be grateful for it? Experts believe that about 50% of such temperament is genetic, but the rest comes from experience, so there's ample opportunity for change. 'Kids and adults both can choose how they feel and how they look at the world,' says Andrew Greene, principal of Candlewood Middle School, who says that realization was one of the lasting legacies of Dr. Froh's research there.

For older children and adults, one simple way to cultivategratitude is to literally count your blessings. Keep a journal and regularly record whatever you are grateful for that day. Be specific. Listing 'my friends, my school, my dog' day after day means that 'gratitude fatigue' has set in, Dr. Froh says. Writing 'my dog licked my face when I was sad' keeps it fresher. Some people do this on their Facebook or MySpace pages, or in one of dozens of online gratitude groups. There's an iPod app for gratitudejournaling, too. The real benefit comes in changing how you experience the world. Look for things to be grateful for, and you'll start seeing them everywhere.

Delivering your thanks in person can be particularly powerful. One study found that fourth-graders who took a 'gratitude visit' felt better about themselves even two months later -- particularly those whose moods were previously low.