Research has shown time and time again that being grateful is good for your health, mood and general well-being. In fact, it’s one of the easiest things you can do to increase your mental health. But if you can’t remember the last time you sent a real thank-you note, a recent study may explain why.

The research, published recently in Psychological Science, says people chronically underestimate the power of expressing gratitude and overestimate how awkward it will be, which may keep them from engaging in the simple but impactful practice.

“Saying thanks can improve somebody’s own happiness, and it can improve the well-being of another person as well — even more than we anticipate, in fact,” says study co-author Amit Kumar, an assistant professor of marketing at the University of Texas at Austin’s McCombs School of Business. “If both parties are benefitting from this, I think that’s the type of action we should be pursuing more often in our everyday lives.”

Kumar’s research involved a series of experiments. Each one differed slightly, but the general concept remained the same: People were asked to send a letter to someone in their life, expressing gratitude. Before sending the letters, the writers were asked about how they expected the recipient to react. Then, the researchers polled the recipients about their actual reactions.

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They found that writers consistently misjudged how their letters would land, overestimating awkwardness and underestimating the recipients’ reported mood and surprise at receiving the note. Kumar says that imbalance points to different priorities and concerns from writers and recipients.

“[Writers] think about things like, ‘Am I going to get the words just right and am I going to be articulate?’ That might be a barrier to actually sitting down and writing the thing,” he says. “But when you’re the recipient of something like a gratitude letter, you tend to evaluate things on the basis of warmth and prosocial intent. As long as somebody’s expression is sincere and warm and friendly, recipients are often going to have a very positive reaction to that.” (For what it’s worth, the study also found that recipients tended to view the letters as warmer and more articulate than the writers thought they would.)

The researchers also surveyed writers before and after they composed their notes, and found that writing the gratitude letters consistently put them in more positive spirits — a finding in keeping with plenty of existing research on the mood-enhancing effects of gratitude.

The new study didn’t look at whether other forms of expressing gratitude — like sending a quick text message, or thanking someone in person — would have different effects. But Kumar says the broader takeaway is that we shouldn’t let our own self-consciousness stand in the way of giving genuine thanks. To make it easier to follow through, he suggests keeping cards on hand, so you can compose a note whenever the mood strikes.

“Writing gratitude letters seems to come at little or no real cost. People were composing these really thoughtful messages in just a matter of minutes,” Kumar says. “The broader message is that people should express gratitude more often, and precisely how you go about doing that might not matter that much.”

Write to Jamie Ducharme at jamie.ducharme@time.com.