If you're still in the market, don't respond emotionally now. Let your asset allocation be your guide. As long as you're comfortable with the overall risk level of your portfolio, you're probably OK long-term. Stick to your investment plan, and consider that you might be benefiting from dollar-cost averaging, which means you're buying more shares when prices are low and fewer when prices are high.

Short-term, keep money you'll need in three to five years in more conservative, liquid investments. And keep saving for retirement. It's still far enough in the future for your nest egg to weather market highs and lows.

In your peak earning years. Hang on and go for growth. From ages 45 to retirement, chances are you'll be in your peak earning years. If you're not already on track, now's the time to focus on saving more and growing your savings. Cash investments may feel safe short-term, but long-term they're far from it. Right now, returns on money markets and Treasuries are negative after inflation. So putting your retirement savings in cash investments doesn't make long-term sense. Over time, stocks have been the best defense against taxes and inflation. Even through events like the Great Depression, major wars and the oil embargo, statistics show that, though vulnerable during the short-term, stocks have been resilient long-term. Is today any different?

Just make sure you keep an emergency fund to cover three to six months of vital expenses in money market accounts or interest-bearing FDIC-insured accounts -- and be mindful of not investing the money you will need in the next three to five years in the stock market. That way you shouldn't be forced to sell in a downturn.

Facing retirement. Protect yourself.

As you get into retirement, you'll want to invest more conservatively no matter what the market is doing. A gradual shift to fixed income investments like bonds and CDs can make sense at this time of life. Market volatility is never comfortable, but now particularly, you'll want to reassess your feelings about risk. An ideal asset allocation would maintain the potential for a certain amount of growth, while protecting your assets and providing income.

Then take a good look at cash flow needs and your spending patterns. Try to keep a full year's (or more) worth of spending in cash so you don't need to pull money out of your equity portfolio during a bear market (with another two to four years' of reserve in fixed income). It's never easy, but in times like these, controlling your spending can be one of your best strategies.

Keeping your eyes on your goal can be difficult at any age and in the best of times. But now, when times are tough, it may be more important than ever. While you can't control the markets, you can control how you respond. And to me, the best response is to keep saving, manage your spending, and stay focused on the long term.