NEW YORK (FORTUNE) - Look up "retire" in Webster's and the first definition is "to withdraw, as for rest or seclusion" - or maybe for just going fishing. But more and more, people bowing out of long corporate careers are doing anything but.

AARP surveys show that 70 percent of Americans want to work as long as they're able to. Other polls reveal a startling optimism about just how long that might be.

More from Fortune Will Mmmhops be a hit? NBA confirms L.A. Clippers sale to ex-Microsoft CEO Steve Ballmer FBI and SEC probe into Carl Icahn and golfer Phil Mickelson FORTUNE 500 Current Issue Subscribe to Fortune

Photo Gallery See more photos

When Yahoo surveyed thousands of would-be entrepreneurs a couple of months ago and asked, "At what age do you think it would be too late to start your own business?" 72 percent of respondents aged 55 and above answered "never."

The five people profiled here have each embarked on an adventure that combines a long standing passion with a profit motive. Who knows? Maybe their experiences will spark an idea or two to help you start planning your own second act.

See a gallery of unusual retirement roles.