This new year, instead of picking up a habit that requires a fancy gym membership or new running shoes, what if you choose one that doesn’t cost anything at all?

Most of us show gratitude in passing, like when a barista hands over our coffee or a co-worker does a small kindness. But what we may not know is how doing so affects our well-being and relationships.

“One thing that intrigues me about gratitude is we often think we are doing it for others, to make others feel good,” said Farnoosh Nouri, a clinical assistant professor of counseling at Southern Methodist University. “In reality, what it does to our body, to our immune system, to our cardiovascular health is incredible.”

Bringing gratitude into focus comes at a time when more than 6 in 10 adults in the United States say societal division is a significant source of stress in their lives. And half or more of adults say they feel isolated and left out or lack companionship often or some of the time. Here’s what research suggests about gratitude — and practical ways to incorporate it in your life.

Gratitude is recognizing that something good has happened and attributing it to another person or, for some, a higher power.

“If you know someone is intending to help you or they are doing it for benevolent reasons because they care about you, you end up feeling more grateful,” said Jo-Ann Tsang, an associate professor of psychology at Baylor University. “If you suspect someone got you a gift because they are trying to manipulate you or get something from you, then your gratitude is going to be a lot lower.”

The origin of gratitude

Tsang said gratitude may have arisen in human evolution to encourage reciprocity. In 1971, evolutionary biologist Robert Trivers coined the term “reciprocal altruism” to explain why animals — especially those not related to each other — will help one another, even when it comes at a cost. Applied to humans, Tsang said, the theory suggests gratitude may motivate us to return a favor, increasing the chances that both people benefit.

Other research by social psychologist Sara Algoe suggests gratitude helps people find partners who are responsive to their needs, strengthening close relationships over time.

Work by scientists Martin Nowak and Sebastien Roch also links gratitude to a phenomenon called “upstream reciprocity” — when receiving help from one person makes someone more likely to be generous to someone else.

Taken together, the body of gratitude research suggests that the emotion may have played an important role in human social evolution and helps explain why it shows up across different cultures.

Benefit the body

Research suggests that expressing gratitude can benefit the body in several ways. In the brain, it can lower levels of the stress hormone cortisol — which may be linked to less inflammation elsewhere in the body — and boost feel-good chemicals such as dopamine and serotonin.

Gratitude may also strengthen the connections between different parts of the brain, Nouri said. That could matter for conditions such as anxiety and depression, in which communication between brain regions involved in emotion regulation may be disrupted. When a person is thinking about gratitude, Nouri added, brain scans have shown increased activity in such areas.

It’s unclear, however, whether practicing gratitude can meaningfully improve mental health conditions. A 2021 review of 70 studies found that people who reported higher levels of gratitude tended to report lower levels of depression. But a 2020 review of studies found gratitude-based interventions produced only small improvements in depression and anxiety, suggesting people should still pursue conventional treatments rather than focusing on gratitude alone.

Other benefits of gratitude include better cardiovascular health. A 2022 study found that gratitude and optimism were linked to a drop in heart rate and blood pressure.

Gratitude can even help our sleep. A 2009 study found that grateful people go to bed with fewer stressful or negative thoughts that keep them awake and with more calm, positive thoughts that make it easier to fall asleep.

Tips on practicing gratitude

Ready to show more gratitude in your life? Nouri and Tsang recommend the following tips:

Keep a journal to write down what you’re grateful for. This can help build a habit of seeing good things in your day-to-day.

Write a letter to someone in your life saying why you’re grateful for them and give it to them. “You not only get the awareness of what you’re grateful for, but because you’re giving it to someone else, you get to see their reaction,” Tsang said. “It strengthens your relationship.”

If letter writing isn’t your style, text three people you are grateful for and tell them why you are.

Take a deep breath before expressing gratitude. This can help relax the mind and reduce stress, Nouri said.

Don’t force gratitude, especially in situations where you do not feel valued or appreciated. “If your needs are not being met and you’re trying to address that by just being grateful, then that can also be an unhealthy thing,” Tsang said.

Miriam Fauzia is a science reporting fellow at The Dallas Morning News. Her fellowship is supported by the University of Texas at Dallas. The News makes all editorial decisions.