Those of us who (try to) exercise regularly often do so with our weight or overall health in mind. Both great reasons, obviously. But there’s another benefit to staying active: It could make you a happier person.

“Exercise on a regular basis can keep your mood elevated,” says Ramona Braganza, a fitness expert and celebrity trainer whose clients have included, among others, Jessica Alba, Halle Berry, Scarlett Johansson, Zac Efron and Ryan Reynolds. “Mood swings don’t occur as much, and overall wellness is achieved when balance takes place in the body.”

Exercise’s mood-boosting benefits were recently underscored by researchers at the University of Cambridge in England, who asked more than 10,000 study participants to track their happiness and physical activity using a specially developed smartphone app. The participants’ self-reported activity data (the researchers asked them what activities they were engaged in the last 15 minutes) was then tracked against information collected directly from built-in activity monitors (accelerometers) on their phones.

At the end of the 17-month-long study, published in the journal PLoS One, the researchers concluded that people who are more physically active are happier than those who are less active. “We found that, regardless of whether we looked at self-reported physical activity or physical activity sensed via the accelerometer on their phones, people who were on average more active were also on average happier,” says study co-author Gillian M. Sandstrom, Ph.D., who contributed to the work as a postdoctoral research assistant at Cambridge and is now a lecturer at the University of Essex.

What’s more, the study, which sent notifications to participants asking them to fill out surveys twice each day, determined that people are happier in the time period in which they are engaged in physical activity. When participants reported that they had been more active — walking, running or cycling, as opposed to standing, sitting or lying down – as well as when their phone’s accelerometers indicated that they had been active, “they also reported being in a better mood,” Sandstrom says.

Still, while the study shows a link between exercise and happiness, Sandstrom notes that it does not prove that exercise causes happiness. In fact, the researchers believe the relationship may go both ways. “We suspect that being happier probably causes people to be more active, and being more active causes people to be happier, resulting in a positive feedback loop,” she says.

The bottom line, Sandstrom says, is that exercise may improve not only our physical, but also our mental health. “Adding a little more physical activity to your day, even if it’s not rigorous exercise, might have the added bonus of making you a little bit happier,” she says.

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Amy Reiter is a writer and editor based in New York. A regular contributor to The Los Angeles Times, she has also written for The New York Times, The Washington Post, Glamour, Marie Claire, The Daily Beast and Wine Spectator, among others, as well as for Salon, where she was a longtime editor and senior writer.