Feel like crying over missed opportunities? Check out the following returns for several notable stocks over the past two decades:

Company

20-Year Average Annual Return

Express Scripts (Nasdaq: ESRX)

33%*

Dell (Nasdaq: DELL)

33%

Paychex (Nasdaq: PAYX)

24%**

Leucadia National (NYSE: LUK)

24%

TJX (NYSE: TJX)

20%

Kohl's (NYSE: KSS)

18%*

Lowe's (NYSE: LOW)

17%

Source: Yahoo! Finance. *Over past 17 years. **Over past 19 years.

A $5,000 investment in Lowe's 20 years ago would be worth $125,000 today. The same investment in Dell would be more than $1 million! Truly, one stock can change everything.

So, why didn't you buy them 20 years ago? Why aren't these amazing returns yours? Why isn't your portfolio home to a few millionaire-maker stocks?

What stopped you?
There are lots of reasons you might not have bought these companies 20 years ago. Maybe you weren't yet awake to the promise of the stock market. (I know I wasn't.) Maybe you didn't have money to invest, even if you wanted to. But even if you wanted to invest and had the means to do so, you probably stilldidn't buy these companies for your portfolio. Why?

Well, with some of them, you didn't expect them to keep generating strong returns. With others, though, you probably didn't see their promise -- because you weren't imagining a future very different from the present. Continued...