The Selfish Reason You Should Be Extremely Generous People who give, especially when they don't have to, are happier, healthier and less stressed.

A few weeks ago, I was passing through Phoenix airport. I'd just picked up lunch and was looking for a place to eat it. I stumbled upon a huge seating area attached to a fast food restaurant. With the exception of a man in a suit at one table, the place was empty. I figured no one would care if I sat down and scarfed my salad.

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Almost immediately, a surly restaurant employee appeared and abruptly announced that if I hadn't bought anything, I couldn't sit there. I thought she was joking. But when I laughed, she just glared at me. Behind her was a sign that read, Welcome to Phoenix: The friendliest airport in America!

Without warning, I became irrationally angry. "I can see that you've got a lot of patrons trying to find a table," I snarled, "Are you going to call security if I don't leave?" Her response was more glaring, and then came the nuclear option: "I'm going to get my manager!" As she marched off, I started shoveling the salad into my mouth, vowing that I wasn't going to leave unless they carried me out. It was not one of my finer moments.

All of a sudden, someone plopped a bottle of water on my table. I looked up to find the man in a suit from the other table handing me a receipt. He grinned and declared, "You just bought a bottle of water! Now, they can't kick you out. Enjoy your lunch!" Before I could register what had happened, he was gone.

I felt equal parts inspired (by Suit Man's behavior) and embarrassed (by mine). I'd chosen to argue when I didn't have to; he'd chosen to give when he didn't have to.

Wow, what a guy! I thought, as I imagined Suit Man's Life of Generosity. His family probably treasured him. His coworkers probably adored him. And his blood pressure was almost certainly lower than mine.

Indeed, a Life of Generosity has many scientifically supported benefits. Here are a few especially interesting examples of how people like Suit Man lead better lives:*

• Generous acts trigger the reward center of our brains, giving us a high not unlike the high of "sex, drugs and rock and roll." Seriously.
• Being generous to your spouse is one of the top three predictors of a successful marriage (perhaps I just saved you hundreds of dollars in marriage counseling? If so, you're welcome).
• Generosity makes us happier. In one study, people who helped their coworkers were more satisfied with their lives almost 30 years later!
• When we experience events like illness, crime or unemployment, helping others buffers us from stress, which makes us less likely to die in the years that follow. Yes, you read that right.

Why Are We So Stingy?

Despite generosity's huge payoffs (and the fact that humans are wired to be this way), we can be surprisingly stingy. The vast majority of Americans -- 76 percent! -- do not volunteer at all. Only 10 percent donate blood. And 30 percent report not helping their friends or neighbors [Face palm].

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When was the last time you could have helped someone, but didn't? Perhaps you rushed past a person begging for money on the street. Or a coworker sought your help, but you politely declined because you had too much going on. Or maybe a stranger asked you for a favor and you refused. We invent so many reasons to justify our selfishness and cynicism. But when you weigh them against the benefits of generosity, generosity almost always wins.

As I pondered Suit Man's behavior, I realized that I was dangerously close to a life of subtle selfishness. Even though I'd do anything to help the people I care about, I am less generous when I don't have to be. And that day I had a long list of reasons for this benign neglect: I was tired, I was overcommitted, I was in a bad mood, etc. If the roles had been reversed, and Suit Man had needed my help, I'm not sure I'd have done the same.

How did I get here? I wondered. There was a time when I went out of my way to help others, even when I didn't have to. When I worked at Starbucks in college, we had our fair share of customers who wanted to yell at us because they were having a bad day. One of my favorite things to do was to hand them their coffee, flash a huge smile and say, "This one's on me!" They would always look shocked, then apologize and thank me for making their day better. And I, of course, felt fantastic!

I wanted to be that person again.

Strengthening Our Generosity Muscles

We live in a tough world—the demands placed upon us (and those we place on ourselves) can feel all-consuming. It can be too easy to deny help when it's difficult, or when we don't have to. But the research on generosity is clear: We don't see benefits unless we make generosity a lifelong habit.

In an illuminating TED talk, entrepreneur Sasha Dichter describes an experiment where he said "yes" to everything for one month (I believe this was also the premise of a mediocre Jim Carrey movie). The reason was that Dichter realized he'd been saying no too often and wanted to create a "new habit and a new reflex." Just days into his experiment, he started feeling like a generous person again.

So, inspired by Suit Man and Sasha Dichter, here is my solemn vow: Starting right now, I'm adding one generous deed every day—something I don't have to do, but want to do.

And here's my challenge to you: Don't just give occasionally, or when it's easy, or when you're in a good mood. Give more than you have to, more often than you have to. As psychology professor Dr. Barbara Fredrickson points out, generosity "create[s] chains of events that. . . trigger upward spirals that transform communities." In other words, give to others, and change the world. And who doesn't want to be a part of that?

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*If you're interested in learning more about the benefits of generosity, I enthusiastically recommend my colleague Adam Grant's book, Give and Take: Why Helping Others Drives Our Success. Grant is not only a brilliant thinker, he truly lives his principles and is one of my personal heroes.

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