The economy is poor, retirement funds are down, and wages have been stagnant for years. Workers across all generations are feeling the effects, especially the baby boomers who can't afford to retire, says John Sweeney, human resources knowledge adviser for the Society for Human Resource Management.

"Baby boomers can't afford to retire because their homes are under water," Sweeny says. "They still have a mortgage in many cases and haven't done a good job at saving for retirement because, let's face it, salaries and wages for a lot of the middle class have been stagnant since the mid-1980s."

But sometimes delaying retirement isn't always about finances, says Allen Steinberg, senior consulting attorney and principal of AON Hewitt. Staying in the work force provides a sense of identity, and many older employees aren't ready to leave behind their self-worth. Working provides psychological benefits as well as financial benefits.