Why Can't We Follow Simple, Good Money Advice?

Experts explain why it’s so difficult to follow two basic guidelines: Save and don’t overspend.

"Retail therapy"—the act of shopping and spending to improve one's mood.

So what happens if we do some or all of these things? Can we change? Absolutely, every personal finance expert and psychologist out there seems to think. But they all say it takes some serious commitment to re-wire our behavior and mindset. "Many people don't want to do the work," Manza says. "It's just too hard. But it is doable."

Simon Rego, a licensed clinical psychologist at the Montefiore Medical Center in New York City, agrees, offering up the idea, for instance, that you can budget by making it harder to spend money. "It's harder to overspend if you don't have any money or credit cards available. So, restrict access to them," Rego says.

He suggests locking away credit cards or shredding them if you can't trust yourself with them, or carrying only the minimum amount of cash you need every day.

But Rego also observes that we let our moods influence how we think and act. So if you're worried that the minimum won't cut it and you've trapped your credit card in an ice cube in the freezer, odds are, you'll melt it free before long.

Don't feel too bad, though. Making bad financial choices – while knowing they're bad – is universal, according to Robert Epstein, a psychology professor at the University of the South Pacific and a senior research psychologist at the American Institute for Behavioral Research and Technology.

"Research on self-control over the past few decades shows clearly why people overspend," Epstein says. "When immediate rewards are available, most people ... tend to go for them, even when those rewards are associated with delayed punishment."

[See: 10 Signs You Shop Too Much.]

If that wasn't the case, Epstein says, people would never have unprotected sex or wolf down big slabs of chocolate cake when they're already packing on the pounds. No one who knows they're likely to get a hangover would drink excessively, and there wouldn't be drug addicts.

"I call those kinds of rewards 'dark rewards,'" Epstein says. "Because money will get you just about any reward on the planet when you have some in your pocket or bank account. Or when a bank gives you a credit line, you'll tend to spend now, even if the delayed consequences are negative."

The good news is that most people can learn some degree of restraint because the payoff of not overspending and of saving is high, Epstein says. After all, there's something comforting about having a lot of money in the bank. But he has bad news for some people – think of that ne'er-do-well cousin of yours who never seems to be able to hang onto money.

"Some people," Epstein says, "those we call 'impulsive' – have virtually no ability to resist the dark rewards."