Do you dream of retiring and seeing the world before you're 60? There are ways to achieve your goal -- if you plan carefully.

©iStockphoto/Jacom Stephens

It's every working stiff's dream: saying sayonara to the daily grind while you still have your own teeth. In our early retirement fantasies, we're traveling the world, healthy and in the prime of our lives, visiting those hard-to-pronounce countries we've always talked about and sampling the finest local fare.

Surveys show that more than half of workers between the ages of 30 and 50 plan to retire before they're 60 [source: MSN]. But there's only one problem with this wishful thinking: Retiring early is easy, but making your money last is hard.

One problem with saving up for early retirement is that we tend not to think beyond those first few glorious years of good health and full checking accounts -- we don't do the long-term math. If the average male life expectancy is 75.2 and we retire at 55, then our savings, stock market investments and 401(k) accounts need to last for 20 years. And what if we live even longer than average?

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­And don't forget that life can get tricky during those last five or 10 years. Very few fortunate souls drift away in their sleep at age 88 without ever having major surgeries, hospitalizations or chronic (and expensive) conditions to manage -- not to mention the ever-increasing costs of medical insurance and prescription drugs.

While we tend to overestimate our health, we underestimate our post-retirement financial needs. A 2002 survey found that only 17 percent of workers thought they'd need 80 percent of their salary after retirement. Forty percent thought they'd be fine with 60 percent of current earnings [source: MSN]. That might suffice for a few good years, but the longer you live, the less chance your money will last.

Furthermore, isn't it possible that traveling the world and living out of a suitcase could get pretty tedious? Did you ever think that you might be bored without a day job? Do you have enough hobbies and interests to sustain you for 20 to 30 years without business trips, deadlines and daily meetings?

But don't get discouraged. If you're serious about retiring early and dedicated to making it work, you can make it happen. All it takes is some serious financial planning, a strict budget and some good old-fashioned luck.

So how do you start planning for an early retirement? What are the most important calculations? What are some common mistakes? Read on to find out.