Do you remember the last time your partner took out the trash?

More importantly, do you remember how you reacted to that small act of kindness?

Couples who take a moment to express gratitude when their partners do something nice — whether it’s taking out the trash, mowing the lawn or picking up their favorite coffee drink on the way home — not only get a temporary boost of happiness, but feel better about the relationship overall.

Those feelings can last for days, weeks, and even months, according to recent research.

University of North Carolina at Chapel Hill psychologist Sara Algoe was one of the first to demonstrate this affect. In one of her studies, she had each member of a couple keep a weekly journal. In it they listed everything their partner had done for them in the previous seven days that made them feel grateful, along with how each act of kindness made them feel and how connected they had felt to their partner.

On the days when they reported feeling more grateful for their partners’ acts of kindness, they also reported feeling more connected to him or her. Those feelings lasted into the following day.

What mattered, then, wasn’t how often someone in the relationship did a thoughtful thing — it was how grateful the partner reported feeling about it.

More recent research suggests that feelings of gratitude affect relationships for far longer than a few days.

series of studies by University of California, Berkeley psychologist Amie Gordon found that the more grateful couples were, the more likely they were to still be in the relationship nine months later.

Being grateful, Gordon wrote in a recent blog post for Psychology Today, isn’t just about saying thank you. It’s about feeling lucky to have a caring partner in the first place.

“My definition of gratitude includes appreciating not just what your partner does, but who they are as a person. You’re not just thankful that your partner took out the trash — you’re thankful that you have a partner who is thoughtful enough to know you hate taking out the trash.”

These findings are based on the idea that gratitude itself can generate more positive thinking, a notion bolstered by dozens of studies in individuals and couples.

Happy couples can make it seem like it all comes naturally, but in reality any strong, quality relationship requires a hefty amount of work. If you want to make your relationship stronger — and you’re willing to put in the effort — gratitude can help you and your partner feel happier and more connected.

Originally published on Business Insider.

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