Potty train. Pull all-nighters. Work. Pay taxes. Retire. Play golf. Die.

Such is the natural order of things in life (with a few substitutions allowed here and there). But changes are afoot; call it an evolution or a severe reaction to the market turmoil. Whatever the reason, there's no denying this: Retirement is no longer about not working anymore.

In recent years, a clear trend has emerged as more and more people say they plan to continue to work long past the traditional age of retirement. An MFS Investment Management survey of 55-to-75-year-old workers found that just 16% said they planned to retire and never work again.

Why? Let us count the ways.

Why Gramps is getting a job
Let's start with the obvious: Money.

Let's face it. If you haven't saved enough by the time you reach retirement age, your options are limited. They include:

  1. Refusing to leave your cubicle even after your official retirement send-off party.
  2. Preparing for a gruesome retirement. (Click that link to get to the gore.)
  3. Starting some good savings habits now, such as contributing to the right accounts, picking the right investments, and starting to save enough. Learn how with the 5-Minute Retirement Plan.
  4. Undergoing an extreme retirement makeover.

Another reason more retirees prefer to keep on their work overalls is peace of mind: Perhaps you have saved adequately but are uneasy about the ability of your money to really last as long as you do. The longer you keep money coming in, the less of it you have to crack out of your nest egg. Plus, in many cases, you can postpone taking Social Security or other benefits, which may result in a higher benefit when you do start collecting.

Finally, there's plain old boredom: Sure, many retirees plan to take time off and see the world. But at some point, they return home ... and then what? Plain and simple, many retirees have had trouble finding fulfilling ways to take up all the extra time.

Of all the reasons to continue working, if I were you, I'd gun for that last one.

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Dayana Yochim already did a stint in fast food retail. She's hoping that she won't need to hone her sandwich-making skills again to make it through retirement. The Fool's disclosure policy -- although already a well-balanced meal -- would actually like fries with that.