Your wellness challenge for this week is to identify someone you are thankful for and let them know. Try to do this four days out of the week (or more)! Besides making that person feel good, here are some ways that expressing gratitude will make you feel good, too.

“There is a magnetic appeal to gratitude,” says Robert Emmons, a professor of psychology at the University of California, Davis, and a pioneer of gratitude research. “It speaks to a need that’s deeply entrenched.” It’s as if we need to give thanks and be thanked, just as it’s important to feel respected and connected socially. From an evolutionary perspective, feelings of gratitude probably helped bind communities together. When people appreciate the goodness that they’ve received, they feel compelled to give back. This interdependence allows not only an individual to survive and prosper but also society as a whole. It’s easy, in these modern times, to forget this, however. We’re too busy or distracted, or we’ve unwittingly become a tad too self-entitled. We disconnect from others and suffer the consequences, such as loneliness, anger, or even a less robust immune system.

“Gratitude serves as a corrective,” says Emmons. But by gratitude, he doesn’t mean just uttering a “Hey, thanks” or shooting off a perfunctory e-mail. He means establishing a gratitude ritual, whether it’s a morning meditation of what you’re thankful for, a bedtime counting of blessings, or a gratitude journal. This concerted, consistent effort to notice and appreciate the good things flowing to us changes us for the better on many levels, say gratitude experts. Here’s how.

1. You’ll feel happier.
In a seminal study by Emmons, subjects who wrote down one thing that they were grateful for every day reported being 25% happier for a full six months after following this practice for just three weeks. In a University of Pennsylvania study, subjects wrote letters of gratitude to people who had done them a major service but had never been fully thanked. After the subjects personally presented these letters, they reported substantially decreased symptoms of depression for as long as a full month.

2. You’ll boost your energy levels.
In Emmons’s gratitude-journal studies, those who regularly wrote down things that they were thankful for consistently reported an ever increasing sense of vitality. Control subjects who simply kept a general diary saw little increase, if any. The reason is unclear, but improvements in physical health (see below), also associated with giving thanks, may have something to do with it. The better your body functions, the more energetic you feel.

3. You’ll get healthier.
A gratitude practice has also been associated with improved kidney function, reduced blood-pressure and stress-hormone levels, and a stronger heart. Experts believe that the link comes from the tendency of grateful people to appreciate their health more than others do, which leads them to take better care of themselves. They avoid deleterious behaviors, like smoking and drinking excessive alcohol. They exercise, on average, 33% more and sleep an extra half hour a night.

4. You’ll be more resilient.
When we notice kindness and other gifts we’ve benefited from, our brains become wired to seek out the positives in any situation, even dire ones. As a result, we’re better at bouncing back from loss and trauma. “A grateful stance toward life is relatively immune to both fortune and misfortune,” says Emmons. We see the blessings, not just the curses.

5. You’ll improve your relationship.
A 2012 Journal of Personality and Social Psychology study of more than 300 coupled people found that those who felt more appreciated by their partners were more likely to appreciate their partners in return and to stay in the relationship longer, compared with couples who didn’t feel appreciated by each other. Christine Carter, a sociologist at the Greater Good Science Center, at the University of California, Berkeley, notes that gratitude can rewire our brains to appreciate the things in our relationships that are going well. It can calm down the nervous system and counter the fight-or-flight stress response, she says. You can’t be grateful and resentful at the same time.

6. You’ll be a nicer person.
People can’t help but pay gratitude forward. When appreciation is expressed, it triggers a biological response in the recipient’s brain, including a surge of the feel-good chemical dopamine, says Emmons. So when you express gratitude toward a spouse, a colleague, or a friend, he or she feels grateful in return, and the back-and-forth continues. What’s more, thanking your benefactors makes them feel good about the kind acts that they’ve done, so they want to continue doing them, not only for you but also for others.

Inspired? Research has shown that one of the best ways to home in on the people and the experiences we appreciate is through writing in a gratitude journal. Recording our thoughts, by hand or electronically, helps us focus them, explains Emmons, who says that he, too, does this exercise to remind himself “how good gratitude is. It gives us time to understand better the meaning and importance of people and events in our lives.” Here are strategies for maximizing the benefits:

1. Go for depth rather than breadth. This will help you truly savor what you appreciate, and keep your journal from becoming simply a list of nice thoughts. (Journals like that tend to get abandoned.)

2. Write consistently. But it’s OK if you can’t do it every day. Once or twice a week is enough to boost happiness.

3. Write freely. Don’t sweat the grammar and the spelling. No one else will see this journal unless you want someone to.

4. Don’t think of this as just one more self-improvement project. Rather, it’s an opportunity to reflect on other people and the above-and-beyond things that they’ve done for you, says Emmons. In other words, “it’s not all about us,” he says. “This may be the most important lesson about trying to become more grateful.”