Negative headlines, 500-point-plus swings in the Dow Jones Industrial Average and economic uncertainty continue to fuel investors' fears. While some of those fears may be justified, financial advisers say you can harm your financial future if you let your fear keep you on the investing sidelines.

Here are five big fears that haunt investors and what financial advisers say you can do to overcome them:

Financial adviser Kurt Rozman recently met with a client who was convinced that the Standard & Poor's 500-stock index was going to end up at 'zero by year-end' and that he would 'go broke' if he didn't sell out of the market immediately.

'He envisioned an extremely unrealistic scenario,' says the Brookfield, Wis.-based adviser.

Mr. Rozman explained to the client that for the S&P 500 to go to zero, all of the 500 largest companies in America would need to 'go bust' at the exact same time and that was very unlikely to happen.

When a client is convinced of a 'doomsday' scenario, Brad Klontz, a financialpsychologist in Kapaa, Hawaii, encourages him or her to take a few deep breaths and repeat silently a phrase such as 'relax.' The client can then evaluate the accuracy of his or her thinking and look for evidence to support or refute that position. 'Just because a thought comes into your mind, it doesn't mean it's true,' Mr. Klontz says.

He also encourages clients to put some time between their initialimpulse to react and the actions they wish to take so emotions play less of a role in their investment decisions.

After losing $400 in three months, the 24-year-old son of one of Ben Sullivan's clients decided he wanted to 'bail out on stocks.' Some clients' young-adult children are hesitant to invest in their company's 401(k) because their co-workers' fear of the market's volatility has affected their perspective, says the certified financial planner based in Scarsdale, N.Y.

While 500-plus point swings can be difficult to stomach, swearing off stocks or not investing in a 401(k) can be a big mistake, says Mr. Sullivan.

'When you have a 20- to 40-year time horizon,' he says, 'waiting to invest is likely riskier than losing a small amount in the short term.'

Mr. Sullivan says he encouraged the 24-year-old to hold on to his investmentstrategy and recognize that when he retires, the $400 loss will be 'long forgotten.'

In some cases, the fear of investing in the unfamiliar can be useful since there are some financial products that are too complex to understand and that investors may be better off avoiding, says Jared Kizer, a St. Louis-based investment adviser.

However, when taken to the extreme, investors may lack the diversification needed to meet their long-term retirement goals, he says.

Choosing investments just because they're familiar can also create unintended risk, Mr. Kizer adds.

For a client who invested nearly all of his life savings in his employer's stock, Mr. Kizer demonstrated how he would have a better chance of meeting his retirement goals if he invested in a variety of assets. Mr. Kizer also shared stories of investors who had lost their retirement savings when their employers went bankrupt.

James Miller continues to field calls from some clients asking if they should 'get out of the market now and get back in when things look safer.'

The Chapel Hill, N.C.-based certified financial planner tells them that timing the market isn't the answer. He reminds them that when things look 'safer,' the market will likely be at a much higher level and the clients will have lost out on a significantamount of the upside by that point.

When clients have too much debt and too little cash flow, they often feel that they don't have enough money to invest, says Constance Stone, a Chagrin Falls, Ohio-based certified financial planner.

'It's often because the client's spending is irrational,' she says.

Ms. Stone recently helped a couple in their early 30s with $132,000 in credit-card and school-loan debt scrutinize their monthly spending and find ways to cut back. In the end, the couple realized that by cutting down on expenses, such as meals out, they'd have money to save toward retirement.

'You can start small,' she says.