In light of the stock market's run of huge gains for most of the '90s, most investors would probably be surprised to know that the market's average annual return since 1926 is around 11%. That's right - not 20% or 30%.

"Just" 11%.

The thing you need to understand, however, is that great wealth can be created over time by earning 11% a year on your money.

For example, at 11% per year, your money doubles roughly every 6.5 years. That means in 25 years, your money doubles nearly four times.

That may not sound like much until you run the numbers.

Let's say you have $45,000 in your company's 401(k) plan. Over the next 25 years, that $45,000, growing at 11% per year, will become $611,346. That's without adding another penny to it.

Think about that for a minute. What this means is the following: If you are a 40-year old with $45,000 in your 401(k) plan, you'll have more than $600,000 by the time you retire at age 65. And that is if you stopped investing today and just let the money compound. Obviously, you'll have a lot more if you continue your annual investments.

Bottom line: Don't be too depressed if market returns revert to more normal ranges over the next three decades. Even at "average" market returns of 11% per year, you can do quite nicely investing in the market.