If you're worried about retirement security, your fears are not unfounded. There are many possible threats to your financial stability during your golden years. Knowing the risks -- and being ready with a fast response when things don't go as planned -- can ensure you don't end up struggling to live on a meager income after your savings has run out.

While saving money early in your career, and setting aside as much cash as possible, should help you to live without worry during your golden years, your retirement could still be derailed by four key factors.

Broken piggy bank

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1. Living longer than expected

According to the Social Security Administration, one in four 65-year-olds today will live past the age of 90, and one in 10 people 65 and older will live past the age of 95. Many people underestimate their life expectancy, perhaps because a parent died young, or because they don't realize data on average life expectancy in the United States is measured from birth and doesn't apply to people healthy enough to make it to 65 years old.

Having more years than you'd planned for is great news -- but life can be tough if retirement savings runs out in your 80s or 90s. The best way to ensure that a longer-than-expected life doesn't leave you penniless in your old age is to save more than you think you'll need. But if you've already quit the working world forever, you'll need to find other ways to stretch your funds.

Moving to a lower-cost-of-living area could be one option for you. Or you could try creative approaches like living on a cruise ship, which might be cheaper than assisted living or costly senior communities, and could allow you to fulfill a goal of traveling as a senior without spending your retirement savings too fast.

2. Higher-than-anticipated healthcare costs

Seniors may need to save as much as $350,000 for healthcare expenditures during retirement -- even if they have Medicare coverage. You'll need to start investing early if you want to have enough money to pay your medical bills should you or a spouse develop a serious or chronic condition.

Contributing to a health savings account during your working life is one of the best ways to cover care costs during retirement. An HSA allows you to invest with pre-tax funds, enjoy tax-free growth, and withdraw funds tax-free to pay qualifying expenditures for healthcare services.

If you're already retired and are facing high costs of care, shopping around to get the best prices is vital, especially for care that Medicare doesn't cover. Consider buying prescriptions from U.S.-based online pharmacies to save, and talk with your doctor about finding ways to lower care costs.

3. Investing too conservatively

Investing too conservatively, especially as you near retirement age, could make it much more difficult for you to build a retirement nest egg that will give you the financial security you need. Close to 60% of investors across all age groups focus more on avoiding losses than maximizing investment growth, and 52% of seniors 60 and older are focused primarily on loss avoidance, according to a 2016 Wells Fargo survey.

A portfolio that is too conservative -- too heavy on bonds instead of stocks -- could cost you $344,000 in retirement income, which could mean the difference between a financially secure retirement and struggling to get by on Social Security. The idea that seniors should be invested in risk-free bonds is an outdated one, given that Americans are living longer and bonds now provide almost no return on investments. Instead of being afraid of the stock market, it's better to learn to diversify investments and manage risk, so you can actually grow your investments enough to sustain you for decades of easy living during retirement.

4. Not keeping an eye on your investments -- or fees

An estimated 40% of Americans do not know how their investments are allocated among stocks, bonds, and other investment products, according to a 2016 Prudential Investments retirement-preparedness survey. Among pre-retirees, three-fourths of survey respondents indicated they were aware they needed to do more to prepare for retirement -- but 40% didn't know where to start. The wrong asset allocation could expose you to more risk than is safe, or could deprive you of growth opportunities as you reach your retirement years.

As problematic as it is not to understand investment allocation, it's even worse to fail to understand fees associated with your investments. A 1% difference in 401(k) fees over the course of your working life could reduce your retirement account balance by as much as 28%, according to the U.S. Department of Labor. This could mean hundreds of thousands of dollars less for you during retirement.

While it may seem daunting, the first step is simply to read your quarterly disclosure of expenses and fees, and review your statements to find out where your money is invested and what you're being charged. If something seems off, it's worth exploring further -- even if you need to talk with a trusted financial advisor to get help.

Christy Bieber has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.