There are few things as pointless as the mailings I occasionally get from my credit card companies, with checks ready for me to use "for my convenience." I don't want them, I didn't ask for them, I'm not going to use them, and on top of it all, they're boring. (If they trouble you, too, you can opt out of getting them, you know.)

So I was surprised the other day to see a line on a mailing from Citigroup (NYSE:C) that kind of inspired me. It said: "It's not a check. It's whatever you want it to be."

How true! It may look like just a piece of paper, but it can represent that large-screen TV you want so much, or a trip to Alaska to see the Northern Lights. Dollars (and checks) are more than they appear, after all. They represent opportunities.

The dark side
Of course, if you use those checks and end up adding debt to your credit card account that you can't pay off when the statement arrives, you haven't done yourself a favor. Yes, a check might have been turned into a nice new set of living room furniture for you. But a new $3,000 debt on your credit card can also turn into $30,000 or more of debt over a decade, if you just can't pay it off and you're being charged the steep interest rates many cards inflict.

So yes, the money can be anything you want, but it can also threaten to ruin you financially. Those slips of paper arriving in the mail can be dangerous things -- and not just because of the potential for paper cuts!

The bright side
The problem with the scenario I described earlier is that it's reckless to buy things you can't afford. But if you save and invest, you can turn money you do have into lots of things you want.

Let's take a minute to look at how money grows, because it's really a beautiful thing. Remember that the overall stock market has grown, on average, by about 10% annually over long periods. That's enough to turn a $10,000 investment into over $25,000 in 10 years, and you'll crack the $100,000 after 25 years.

So you clearly have choices. You can buy a large-screen TV and new furniture now for $10,000, or you can invest it, and end up with a year or two's living expenses come retirement. You can afford to travel around the world with it in your golden years. You can leave a beautiful bundle to your children. That money in your pocket or your bank account -- it can be whatever you want it to be. It can help make many of your dreams come true. Don't think of it as just money, or just numbers, or just what you have to accumulate to be responsible.

Beat the market
Better still, you may be able to grow your money even faster than the overall market. There are plenty of stocks and mutual funds that provide strong value while outperforming the market over long periods (though no such future performance is ever guaranteed). Check out these 10-year averages -- keeping in mind that the S&P 500 has averaged around 3% annually in the same period:


10-Year Avg. Annual Growth

Turned $10K Into...

Illinois Tool Works (NYSE:ITW)



Estee Lauder (NYSE:EL)



Fortune Brands (NYSE:FO)



PepsiCo (NYSE:PEP)



General Dynamics (NYSE:GD)



Jacobs Engineering (NYSE:JEC)



Data: Yahoo! Finance.

So think twice before spending money without thinking much about it. Think about what else you could do with it. Think about how it can best serve you. Think about what you really want to do, and focus your finances on your most important dreams and goals. A simple market-meeting index fund can be all you need, but you might also want to add a few individual stocks or managed funds to your mix.

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Longtime Fool contributor Selena Maranjian owns shares of PepsiCo. Try our investing newsletters free for 30 days. The Motley Fool is Fools writing for Fools.