You've probably been told a dozen reasons why it's never too early to start saving seriously for retirement. Add this one to your list: Sometimes, retirement comes sooner than you expect.

The Fidelity Research Institute recently found that 55% of retirees surveyed left work earlier than they had planned; they named health as the biggest reason. These folks ran into an illness or disability that forced them into retirement.

Among the other reasons cited for early retirement, some said their employers offered them a package they couldn't refuse. Others needed the time to care for a relative. Some reached the age when they no longer wanted to work full time, or they qualified for their full benefits.

Only 1% said they retired earlier than planned because they had reached their savings goal.

Another reason to start saving early: Lots of people who expected their expenses to go down in retirement found that they actually rose. Virtually half of all retirees thought they'd spend less money in their years after working. Another one-third thought their expenses would stay about the same. In actuality, only one-third of people saw their expenses fall, and fewer people than that saw their expenses stay about even.

That leaves almost 40% of retirees whose expenses rose, double the number who expected that outcome.

The lesson? You can plan to retire at age 65, and you can plan to keep your expenses in retirement between 70% and 80% of your current spending. But reality can mess with your plans.

That doesn't mean you're helpless. Take a cue from these surveyed retirees, many of whom admitted they had some regrets about their retirement plans.

  • Start an IRA early. Retirees named not starting one early their biggest mistake in retrospect. You can open an IRA pretty much as soon as you start earning income. If you're the stay-at-home spouse of a working man or woman, you'll probably qualify, too. You still have time -- until April 17, to be exact -- to sock $4,000 away to fulfill your 2006 contributions. Then you can get started saving $4,000 toward 2007. Check out this month's issue of Motley Fool Green Light for detailed advice for opening, funding, and investing in an IRA. For more information about the different types of IRAs, and their eligibility requirements, look to the IRA Center.
  • Pay down your debt. Retirees pointed to accumulating too much debt as the second biggest regret that prevented them from being more fully prepared for retirement. You already know that credit card debt can drag you away from meeting your retirement goals. Make a plan to get out of debt and free yourself from those credit card payments. If you're getting closer to retirement, you might want to re-examine all your debts. It could give you some peace of mind to know your home and vehicles have been paid off, too.
  • Plan for your expenses. In your younger days, it's helpful to have rules of thumb that suggest you'll need 70% to 80% of your current income to keep up your standard of living in retirement. As you get closer to that transition, find out whether those rules of thumb apply to you. Figure out which expenses you'll drop and which you'll keep paying. Make sure to add anything new, such as travel or health care, that you're expecting in retirement. You can start making those calculations, and also find out how long your savings will last, in this section of the Retirement Center.

The Fidelity Research Institute survey also found that 18% of workers haven't yet saved a dime for retirement. To maximize the chances that you'll be prepared for whatever life throws your way, break through these barriers and start saving now. You'll have time on your side to help you prepare for whatever comes your way.

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Fool contributor Mary Dalrymple welcomes your feedback. The Motley Fool has a disclosure policy.