Many people work for several decades before they can retire. Portfolios compound, earnings go up and people look toward the finish line as motivation to continue the race. Retirement is a marathon, not a sprint, but a few curveballs can catch some retirees by surprise. Learn More: How Much the Average Middle-Class Retiree Spends Monthly at Age 65 Find Out: I'm a Retired Boomer: 6 Bills I Canceled This Year That Were a Waste of Money Often, boomers end up depleting their portfolios much sooner than expecte ...