Steven Toepfer of Kent State University, Salem, had students in six courses write letters of gratitude to people who had positively influenced their lives. Over a six-week period, the students wrote one letter every two weeks.
After each letter, the students completed a survey to gauge their moods, satisfaction with life and feelings of gratitude and happiness.
The result, Toepfer said, was dramatic. The more letters they wrote, the better they felt.
"We are all walking around with an amazing resource: gratitude," Toepfer said in releasing his study. "It helps us express and enjoy, appreciate, and be thankful and satisfied with a little effort. We all have it, and we need to use it to improve our quality of life."
Sara Algoe of the University of North Carolina at Chapel Hill, studied 65 couples and found that expressing gratitude was immensely important in maintaining a committed relationship, but the expression had to be genuine. If it seemed more like revealing indebtedness, it didn't work.
And psychologist Todd Kashdan of George Mason University found that gratitude -- "the emotion of thankfulness and joy in response to receiving a gift" -- is an essential ingredient for living a good life. But his study, published in the Journal of Personality last year, found a gender difference.
Men, he concluded, are much less likely than women to express gratitude. It's not clear why, but some research suggests that men are more likely to think expressing gratitude invokes indebtedness.
Kashan, who also has a book, "Curious," came up with three essentials for happiness: meaningful relationships, gratitude, and living in the present moment with an attitude of openness and curiosity.
But why, you may ask, would simply saying thanks in a genuine way have such a profound effect? Emmons, of UC Davis, offers these reasons:
"Studies are showing that it is not only feeling gratitude but expressing it in the context of relationships that makes it matter. When we express an emotion, it tends to magnify or amplify the feeling. So expressing thanks makes our gratitude stronger."
It also strengthens our relationships, he said, "so not only do we get the internal, personal benefits but also the external relational elements that are less likely to happen if the gratitude stays silent."
"It is good for the giver, and good for the receiver," Emmons said. "This has been documented in friendships, romantic partners and spouses. One study showed that the mere expression of thanks more than doubled the likelihood that helpers would provide assistance again."
So with all that going for it, why do we sometimes find gratitude so difficult to express?
Maybe it's because we're just never quite satisfied with what we have.
As the longshoreman-turned-philosopher Eric Hoffer said years ago, "The hardest arithmetic to master is that which enables us to count our blessings."
If you made it this far in this column, thanks a million.