NEW YORK (MONEY Magazine) - Unlike wrinkles and paunches, money maturity doesn't automatically come with age. Nor does it necessarily arrive when you land a big paycheck, finally pay off your student loans, buy your first home or say "I do."

No, money maturity is less about reaching a specific financial milestone than it is about achieving a particular state of mind.

How do you know when you're really a financial grown-up? You're well on your way when you realize the following:

Not tomorrow, not when you get a raise, not when you finally pay off your credit cards, but today. You no longer think that once you reach a certain magic salary number, you'll suddenly be able to afford to invest. And you understand that the sooner you start saving, however little, the less painful the process of saving will be.

Consider: If you save just $40 a week, you'll have nearly $13,000 in five years, assuming average gains of 8 percent a year. If from ages 22 to 32 you save about the same amount in a retirement account and you earn the same 8 percent a year, you'll have nearly $500,000 by age 65 -- even if you never save another dime.

Your goal should always be to live on 90 percent or less of your income and save the rest, says St. Paul financial counselor Ruth Hayden.

"If you view that as a set boundary, your life will be forever different, for the better," she says.

Sure, your parents may still lend you a financial hand from time to time. But you don't think they owe you. You're not relying on Mom or Dad to pay for your new car, subsidize the down payment on a house or even let you move back home if you fall on hard times.

This kind of self-reliance means, in part, that you need an emergency fund -- a stash of cash you can use if your car needs major repairs, you're downsized or you are otherwise hit by financial misfortune. Aim to keep enough money in a money-market fund or another safe, liquid account to cover your living expenses for at least three months.

You listen to advice from accountants, planners and brokers. But you don't blindly follow their recommendations, because you recognize that their agenda may be different from yours.

Hayden recalls a mortgage lender who recently told her clients they could afford a house that cost $150,000 more than the other homes they were considering. But "afford" to a bank means the highest possible loan payments you can make based on your income, assets and debt.

"Afford" to you should mean having enough cash left after paying your mortgage, maintenance and property taxes to do something other than hug your front door.

Before you act on any financial advice, always follow up with your own research, whether that means seeking a second opinion or just reading up on the issue. Then do a gut check to make sure you're truly comfortable with the move. After all, it's you who's on the financial hook, not the adviser.

There is no such thing as a perfect investor. You can, however, be a smart one and learn from your occasional but inevitable mistakes. When it comes to investing, after all, you have to risk some loss to garner gains over the long term.

"If you never make a mistake, you're not doing enough with your money," says Ginita Wall, a certified financial planner in San Diego. "The secret is to win big and lose small."

One way to limit your losses and protect your gains: Take some of the emotion out of your investment decisions by setting target prices for particular holdings -- deciding in advance that you'll sell if the price drops or rises by a certain amount.

You have material desires like everyone else. But you recognize that those desires are fueled by an advertising-driven culture that encourages you to feel like you never have enough. You understand that the quest to possess can be never ending unless you consciously apply the brakes.

The true signs of a financial grown-up: Instead of ratcheting up your lifestyle every time you get a raise, you consciously live below your means, value the nonmaterial wealth in your life, such as family and friends, and resist the urge to buy the next big thing simply because you can.

In the end, says James Gottfurcht, president of Psychology of Money Consultants in Los Angeles, you know that you've reached money maturity when you realize that "financial freedom and success go not to those who have the most, but to those who need the least."

Jeanne Sahadi is a senior writer at CNN/Money.com. E-mail your comments to her at starting_out@moneymail.com.