It’s good to be good. When we do for others, we’re often rewarded by a warm feeling and a sense of well-being. Those aren’t just passing thoughts, either. Doing good has lasting health benefits, especially when good deeds are repeated. In a season of drinks, sweets and treats, here’s one way the holidays may make you a little bit healthier.

READ MORE: Ways to Get Energized, Naturally

Giving Makes You Happy

Most people feel good when they give to others, whether it’s a family gift exchange or a donation to charity. You’re probably familiar with the feeling, but only in recent years was the relationship between giving and happiness confirmed by research.

Harvard Business School researchers in 2009 published a paper that discusses past evidence for this relationship alongside original research of their own. The paper examines whether giving promotes happiness or vice versa, and how charities use this to market their causes. They conclude that charitable giving and happiness may indeed have a cyclical effect, and the best way to advertise charities is to appeal to that joy of giving.

READ MORE: Eating Healthfully Improves Mood, Productivity

The amount given may not matter at all. The same Harvard researchers conducted an original experiment in which they gave shoppers money to either spend on themselves or on someone else. Amounts given to shoppers varied between $5 and $20, but when they were surveyed later that day, the dollar amounts were inconsequential. Those who had spent money on others rated their moods better than those who had spent it on themselves.

You may think that happiness is highly individual and therefore difficult to generalize, but studies provide evidence to the contrary. Research shows that once basic needs are met, income level does little to affect overall happiness. Instead, happiness may be influenced more strongly by the perception of wealth relative to others. When it comes to giving it away, the opposite appears to hold true: Those who give a higher percentage of their assets away tend to be happier overall.

Happiness Makes You Healthier

There are known negative health effects of depression and sadness, but what about benefits of feeling good? The connection between happiness and giving may seem obvious to you, but more recent research sheds light on the health benefits of happiness.

READ MORE: The True Impact of Depression

Research indicates that, especially in older people, happiness is good for the heart. In a thorough study of over 200 adults followed over 3 years, London researchers found that happier subjects had lower blood pressure. In the same study, men who were happier had lower resting heart rates, which is an indicator of heart health.

They also found that those who rated their happiness higher had lower levels of the stress hormone cortisol, and that their bodies regulated cortisol more effectively. Cortisol has been implicated as a factor in many health disorders, including Type 2 diabetes and inflammatory conditions.

READ MORE: The Link Between Vitamin D and Disease

In a larger study, researchers looked at several European nations, ranking them in terms of happiness and hypertension. Those countries with higher self-reported levels of happiness had consistently lower levels of hypertension. The happiest nations were Denmark and the Netherlands, while residents of Italy, Greece and East Germany reported they were the least happy.