Tuesday was another ugly day on Wall Street, with many indices at multi-month lows. That news prompted some jittery investors to sell out of their positions out of fear.

But are you ever able to time it right at both ends -- getting out at the right time and then getting back in at the right time? It's almost mathematically impossible to do so.

My executive producer Christa sold some of her stock holdings in mutual funds and index funds because she was worried about the roller coaster ride. She was trying to time the market despite my advice.

The thing is, stock markets are like roller coasters. Christa has decades left until she retires and needs that money. She should not be looking at market timing.

If you are approaching retirement or are in it, you've got to be able to pass the sleep test. Are you overexposed or are you reasonably exposed to stock market volatility? You don't want to be 60 and have all your money in stocks. You need to gauge your risk based on where you are in life.

If you're in your working years, I want you to continue to contribute every pay period to a 401(k) or other retirement plan.

Sure, there are worries out there like Iran, Syria, Lebanon, Israel, China, the European economy, Brazil, and Russia, to name a few. You can go on and on with the list. It never changes; there's a crisis a day that could impact the stock market negatively.

But you can only plan for what you can prepare for, using the most logical way to grow your money over time. The younger you are, the more you should include  stocks in your investment mix in order for your money to grow for you -- and outgrow inflation.