People say that doing good for others is good for you, too. But what, exactly, can charity do for you?

In this study, researchers looked at the volunteer habits of 29,000 people across 29 states. They found that “formal volunteers” (those from organizations and religious groups) reported greater health and happiness than non-volunteers. The more they volunteered, the greater their wellbeing.

Volunteering doesn’t appear to cause better health, per se (rather, healthy people may be more able to volunteer), but it does cause greater happiness. Interestingly, donating money didn’t have the same effect.

If you’re looking to make yourself (and others) happier, put your free time toward a worthy cause.