woman sitting on stool(Photo: Bjorn Wallander)

About a quarter of Americans volunteer, and of those, a third volunteer for more than a hundred hours each year (which, if you think about it, is just two hours each week). When I was growing up, I saw both my parents volunteer countless hours to various causes over the years. Although it might seem like a wise practice to talk to children about the importance of volunteering, in my case my parents sent a very clear message by not talking about it. It went without saying: Of course a person would spend time and energy on important causes. No discussion necessary.

Volunteering our time, energy, and money is the right thing to do — we all know that. Furthermore, studies show that this habit boosts happiness; those who work to further the causes they value tend to be happier and healthier, experience fewer aches and pains, and even live longer. They show fewer signs of physical and mental aging.

And it's not just that helpful people also tend to be healthier and happier; studies show that helping others in itself causes happiness. "Be selfless, if only for selfish reasons" is one of my favorite happiness paradoxes.

Giving back may seem like a stretch time-wise, but it enables us to grow in unexpected ways. We're happier when we're learning something new, teaching someone else, making something better, or fixing something. As William Butler Yeats observed, "Happiness is neither virtue nor pleasure nor this thing nor that but simply growth. We are happy when we are growing."

Volunteering can be a terrific way to foster an atmosphere of growth. You can organize meetings to support your neighborhood school. You can help out in a soup kitchen. You can give an overworked neighbor some free babysitting. By cultivating an atmosphere of growth, you charge your life with energy and happiness.

Also, volunteering allows us to build and strengthen relationships with others. Ancient philosophers and contemporary scientists agree: If there's a single key to happiness, it's strong bonds with other people. Generous acts strengthen our bonds with others, and what's more, studies show that happiness is often boosted more by providing support to other people than by receiving it. I get more satisfaction out of thinking about the help that I've given to others than I do from thinking about how others have helped me (though gratitude is another key element to happiness).

One of the most pernicious myths about happiness is that it's selfish to try to be happier. In fact, research and experience prove just the opposite. Happy people spend more time helping others and are more likely to volunteer and to give away money. They have stronger relationships with their families, friends, and coworkers. They're healthier, and they have healthier habits. Importantly, happiness gives people the emotional wherewithal to turn outward, to think about others, while the less happy are more likely to feel distrustful, isolated, and distracted by their own needs. Being happy doesn't make people want to drink piña coladas by the beach; it makes them want to figure out how to improve rural villagers' access to clean drinking water.

However, while it's absolutely true that helping other people makes us happier, and that those who do feel a distinct "helper's high," it's also true that when we're unhappy, we often find it tough to make efforts to help others. Helping others would probably boost our happiness, but when we're unhappy, we tend to be preoccupied with our own problems.

That's one reason why it's not selfish to strive to be happier: When we're happy, we're more likely to want to make others happy. I've observed this phenomenon in myself. One reason I started my happiness project was that I hoped if my life became happier, I'd become more generous, more thoughtful, more patient — and more eager to find ways to help other people. As Simon Patrick wrote, "If better were within, better would come out." And at least in my case, that has proved true.

One cause for which I now volunteer my time, energy, and money is the New York Public Library. I love the library! Whether you want an excellent book to read, a tutorial on updating your résumé, a place to take a class to learn English as a second language, a great hangout for your teen after school, or a room full of research materials for your Ph.D. thesis about the history of the French Revolution, you'll find people and resources to help you — all for free.

Throughout my life, I've been drawn to libraries. I love the sense of possibility and industry, the quiet company, and all those books. In college, whenever I was feeling blue, I'd go up to the stacks in the enormous main library. These days, I still often visit my neighborhood library in order to work. (Confession: One reason I go is that fleeing my home office is the only way I can resist the siren call of e-mail and the Internet.) Because I love libraries so much, I feel grateful to have the opportunity to help keep them strong.

What's more, although the subject of self-esteem has generated a fair amount of controversy over the last few decades, it's clear that we don't get healthy self-esteem from constantly telling ourselves how great we are or even from other people's telling us how great we are. We get it from behaving in ways that we find worthy of our own respect — such as helping other people.

And just as the research predicts, my small portion of work for the library has made me very happy. I've met many terrific people who share my love of reading and research. I've learned about treasure troves of books and materials that I'd never known existed. I've drawn closer to New York City because I've invested time and energy in one of its best institutions. I can even tell you the names of the two marble lions outside the New York Public Library's main building (Patience and Fortitude).

I'm also deeply interested in the issue of organ donation. My husband has hepatitis C, and while he's in great health now, it's not impossible that he might one day be a candidate for a liver transplant. I appreciate the opportunity to use my time, energy, and money to help further the cause of organ donation. The need for organ donors is pressing, and while about 90% of Americans support organ donation, far fewer have taken steps to sign the organ-donor registry or to tell their families that if the opportunity arose, they'd want to be a donor.

If, at this point in your life, you feel so overtaxed that you don't have one spare minute, one extra dollar, or one scrap of energy to spare, this is something you can do in less than a minute — and know that you've taken an extremely important step toward helping others. Take 30 seconds right now and sign the online registry at organdonor.gov. It's a Secret of Adulthood: Do good, feel good.