NEW YORK (MONEY Magazine) - Look ahead to January. It's sleeting outside. The holidays are over, and all you've got to show for it is a monster credit-card bill and five extra pounds around the middle.

Happy New Year.

If December is a time of excess -- the decorations, the drinks and dinners with friends, the gifts that obliterated the budget that you swore you'd stick to -- January is a time to kick ourselves for spending too much in December.

That's known as buyer's remorse.

Buyer's remorse doesn't afflict only compulsive shoppers. The average consumer spends $700 around the holidays, and Wharton economist Joel Waldfogel estimates that 10 percent of it is wasted on what he calls the "deadweight loss" of Christmas: gifts no one wants.

Why, exactly, do we head to the mall with the best budget-minded intentions, only to talk ourselves into going overboard?

"When you get excited about buying something, what you're imagining is the day you get it or the moment you give it to someone," says Harvard psychology professor Daniel Gilbert. "But a year later, the Porsche is just your car, the same car you drove yesterday. Then the next time, you buy something even more expensive, hoping it'll make you happier for longer. It's a hedonic treadmill."

Yes, giving nice gifts (to others and to yourself ) feels good, but that doesn't mean you should go into debt -- even by 50 bucks -- to do it. The challenge is to stop yourself from splurging when you're standing at the checkout counter.

Here are four strategies that can help.

Breathe Pulling out a credit card can trigger the same rush as a new love affair. "Shoppers can get so caught up in the sensory experience of shopping that they lose track of reality," says Ron Faber, a University of Minnesota specialist in compulsive shopping. But like many love affairs, it doesn't last.

A recent Stanford study found that shoppers who came up with some mental trick that helped them snap out of it reduced impulse purchases, the kind most people regret.

Make a list of what you'll buy and how much you plan to spend, and if you find yourself approaching the register saying, "Ah, what the hell," count to 10. Or step outside. Call your spouse. Whatever works.

Don't get sucked in It's not a bargain if you don't actually need it. Sales and coupons aren't gifts from the shopping gods but ruses designed to get you into the store. One recent study found that coupon-clipping supermarket shoppers spent 8 percent more than the coupon-free.

Avoid plastic Of the $400 billion that Americans spend each holiday season, roughly a third goes onto already overburdened credit cards, according to the National Retail Federation.

A $1,000 flat-screen TV will end up costing $1,070 if you pay it off at 13 percent over 12 months. Use a debit card or cash instead.

Step away from the changing room Shopping expert Paco Underhill says we're twice as likely to buy clothes if we try them on.

So unless it's something you planned to buy anyway, don't.

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