Find a 'retirement' career you'll love

FORTUNE -- Dear Annie: For the past six months or so, my employer has been offering voluntary severance packages, including early-retirement packages that would "bridge" senior managers to a pension. I think the hope is that enough people will volunteer to quit that they don't have to lay anyone else off.

I'm considering taking a package. I'm 54 and eligible to get "bridged" and, although retiring early would mean a substantial drop in pay, that's OK: The youngest of my three kids finally graduated from college in May, my mortgage is paid off, and my wife and I have some financial breathing room for the first time in 30-plus years.

I also have been feeling restless in this job for quite a while now and find myself daydreaming about doing something else. The trouble is, I have no idea what. Can you give me any pointers on how to choose a "retirement" career that will keep me challenged and productive for the next 20 years? --Goodbye to the Daily Grind

Dear G.D.G.: Your question is a timely one, since old-fashioned stop-and-smell-the-roses retirement is fast becoming the exception rather than the rule. Consider: By 2016, more than one-third (33.5%) of the U.S. workforce will be over age 50, up from about 29% now, the Bureau of Labor Statistics reports. Meanwhile, eight out of ten Baby Boomers want to keep working after "retirement," according to research from the American Association of Retired Persons.

Even if they don't want to keep working, many may have to. People in your 46-to-55-year-old age group stand a 43.7% chance of running out of money for basic living expenses in retirement, according to a Employee Benefits Research Institute analysis of a database of 24 million Americans' 401(k)s. Older Baby Boomers, ages 56 to 62, are even more at risk, with a 47.2% chance.

Part of the reason, of course, is that old-style pensions like the one you're luckily getting "bridged" to are vanishing -- replaced by defined-contribution plans like 401(k)s that put the responsibility for retirement saving squarely on employees' shoulders.

So large numbers of would-be retirees are either launching second careers right now or soon will be. Financial considerations aside, Americans in general now live longer, healthier lives than in the past, so that, at age 54, you may indeed have 20 more high-energy years ahead.

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"People need to work," observes Michael Finkelstein, M.D. "They need to be productive and creative, and there are many, many different ways to do that."

Dr. Finkelstein, an internist, speaks from experience: He made a major career change five years ago, when he quit his high-paying job as medical director of Northern Westchester Hospital in affluent Mount Kisco, N.Y., and started practicing holistic medicine. He now runs a Bedford, N.Y., alternative-medicine practice called SunRaven.

Your restlessness in your current job is a feeling he remembers well. "I had a very well-paid, high-prestige job, three kids, a nice home -- it all looked great on paper," he says. "But it didn't feel right. I was working 12- and 14-hour days and losing touch with my family. I needed to make a big change."

Talkback: Would you want a second career in "retirement"? Leave your comments at the bottom of this story.

He offers these 5 suggestions for how to pick your new direction:

Envision your ideal life. When you're daydreaming about doing something else, what are you picturing? Think about "what would your day be like if you were doing something you really loved?" Dr. Finkelstein says.

It may help to think back to when you were in college, or even younger. "What was your dream then? When all doors were open to you, which one did you most want to walk through?" he asks. The answer may point you to your next endeavor: "Can you combine your current skills with that early passion?"

Consider a wide range of possibilities. "What section of the newspaper do you read first? What's your favorite store to shop in, or Web site to browse, and why?" he asks. "Or think about the last thing you Googled, or the last word you looked up -- what was it that interested you enough to take that extra step?"

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Start with a "baby step" toward your goal. "Often, fear of taking too big a leap all at once is what holds people back from doing what they really want to do," says Dr. Finkelstein. "So look for a way to take a small step in a direction that appeals to you."

For example, while still in his old job, Dr. Finkelstein graduated from Dr. Andrew Weil's Arizona Center for Integrative Medicine (integrativemedicine.arizona.edu), doing most of the required course work online. "It took me four years to figure out that I wanted to do this and get up the courage to do it," he says. Take your time.

Redefine "success." "True success isn't necessarily measured in titles or wealth," notes Dr. Finkelstein. "Is your current definition of success your own, or someone else's? What would true success look like in your new career?" Knowing the answer to those questions will give you a goal to aim for.

Be patient. Five years along, SunRaven's "balance sheet still isn't a 'success,' " he says. "There are still obstacles and things for me to learn. But I feel more successful, because I'm moving in the right direction. And unlike before, my relationships with my kids are phenomenal."

Good luck!

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