(OPRAH.com) -- There are many practices from biblical times that are best left in the past. Stoning adulterers comes to mind. As does sacrificing oxen.

But let me tell you about one dusty Middle Eastern custom that deserves a comeback: tithing.

For those who skipped Sunday school, tithing is the practice of giving 10 percent of your annual income to the needy. You donate one out of every ten dollars (or shekels or sheep) to the orphans, the widows, the destitute, or the temple high priests.

Granted, some folks in 21st-century America still tithe (devout Mormons, for instance, are expected to cough up 10 percent). But the practice has largely gone the way of pharaohs and women named Bathsheba. Which isn't surprising. Tithing is hard as hell, especially in these lean times.

I first learned about tithing a few years ago. At the time, I was trying to follow every rule in the Bible -- a journey I chronicled in a book. The Bible told me to tithe. So I tithed.

When I told my wife, Julie, about my plan to tithe, she fretted. In general, she's much more magnanimous than I am. She's a sucker for those charities that send you free sheets of return-address labels with little cartoons of a Rollerblading Ziggy, along with a heartbreaking brochure about lymphoma. I tell her it's emotional blackmail. She ignores me and mails them checks.

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But even for Julie 10 percent is high, especially with the ridiculously expensive prospect of raising children in New York City. Julie asked whether I could count my literary agent's fee as a tithe. She was only half-joking.

"Can you at least do 10 percent after taxes?" she said.

That night I called a friend who's a Lutheran pastor. "You shouldn't get too legalistic," he said. "Give what you can. And then give some more. It should feel like a sacrifice."

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I studied my Bible for insight. It seems that in the time of ancient Israel -- before the Romans took over -- no one paid taxes per se. The tithes were the taxes. And the tithing system was as complicated as any 1040 form. The farmers gave to the priests, the temple-keepers, the temple itself, the poor, the widows, and the orphans. So I decided after-tax tithing was probably okay.

I calculated 10 percent of my projected salary. It wasn't a huge number -- but that was precisely the problem. If I were making $10 million a year and had to give away $1 million, that would have been easier.

Although many modern tithers give to their church, I decided to go directly to the needy. I spent hours browsing the Web site CharityNavigator.org. It's sort of a Michelin guide to aid organizations. (Even this leads to coveting -- they list the salaries of these charity CEOs, and some break half a million.)

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I settled on several organizations focusing on children and widows, two groups the Bible says are always in need. One was called Feed the Children, another Save Darfur.

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The giving was painful. I mean, 10 percent? That would have an impact on our lives. Vacations would need to be scaled back, new furniture would have to wait. It was a huge amount. When I pressed "send" on the donations, my palms got wet, my heart rate spiked.

But it was a pain mixed with pleasure. When the confirmation e-mails pinged in, I felt good. There's a haunting line from the movie "Chariots of Fire." It's spoken by Ian Charleson, who plays a deeply religious sprinter in the 1924 Olympics. He says: "When I run, I feel His pleasure."

And as I gave away money, I think I might have felt God's pleasure. Which is odd. Because I'm agnostic. I don't know if there's a God or not, but still I felt some higher sense of purpose. It was like a cozy ember that started at the back of my neck and slowly spread its warmth through my skull. I felt like I was doing something I should have done all my life.

That feeling of pleasure when giving -- scientists actually call it the warm-glow effect -- isn't strong enough to get most Americans to cough up 10 percent, though. According to the Roper Center for Public Opinion Research, the average American donates about 3 percent of his or her salary to charity.

Low-income workers are the most openhanded set, donating an average of 4.5 percent. (Of course, there are many exceedingly generous high-income people. Angelina Jolie has said she gives away a third of her income. The pastor Rick Warren reverse tithes -- he gives away 90 percent of his profits from his megaselling books.)

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I must confess that I haven't tithed every year since. I'm a quasi tither. This year I donated about 7 percent of my income. Tithing for me is a goal that I want to meet but sometimes don't. (I will, however, be tithing the writer's fee for this article. How can I not?)

I've developed some strategies to help make tithing easier. The key is to make it concrete. Try thinking in terms of time. Every ten minutes of work, you are essentially doing one minute of volunteering for the needy. Six times an hour you're doing a mitzvah! Since I'm a writer, I also tell myself this: One out of every ten words belongs to someone deserving. In that previous sentence, it was the word deserving.

I also try to remember what I teach my sons. Sharing is caring, I always tell them. If my son had two lollipops in his pocket, and a friend asked for one, I'd tell him to fish one out of his pocket and hand it over. It's the proper thing to do. I should practice what I preach.

Finally, I try to think of tithing as a sort of cosmic 10 percent tip. Scientists say that gratitude is like a psychological wonder drug. And by tithing, I'm saying thank you to the universe -- or to God or to fate or to whatever you believe in -- for allowing me to be alive. I want to acknowledge how lucky I am to have food, a roof, a bed, a warm shower, and a father who didn't sacrifice me on top of a mountain. That deserves a donation to the Big Tip Jar in the sky, don't you think?

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By A.J. Jacobs from O, The Oprah Magazine, December 2009

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