CLARKONOMICS: 2008 was a disaster for the many Americans who now have money tied up in the stock market. During the slump of 1987, by comparison, very few Americans were invested in stocks. Today it's completely different because of the popularity of 401(k)s, 403(b)s, IRAs and more.

The average market decline was probably around 40% -- easily the worst since the Great Depression in the 1930s. But if you're one of those people who think you should go to the sidelines and wait things out, think again. That's a big mistake if you're under age 55, and a huge error if you're in your 20s or 30s.

Clark has no idea if 2009 will be a good or bad year for the market. However, it doesn't matter; just look at your time horizon. If you're 40, we're talking about money you won't have to tap for 25 years or so. If you're 30, that 35 years away!

The younger you are, the better. More things are on sale for you at depressed prices. Dollar cost averaging -- where you buy tiny slices of capitalism each pay period -- is your friend. If the market tanks further, you buy even more shares at a depressed price.

So get back in the game to make some money in the long run. For Clark to be wrong about this, capitalism would have to go caput around the world -- a highly unlikely scenario.

In 20 years, you'll want to find Clark and tell him how much money you made because you listened to his words today!