For the past quarter-century or so, the national conversation about retirement has focused on investing. With good reason. Millions of workers suddenly faced the need to learn more about investing as the 401(k) became the primary retirement savings plan for private-sector employees.

But the conversation is changing. Yes, saving is important. But our energies are shifting toward thinking about what kind of work we want to do during the last stage of life. For one thing, we're living longer, healthier lives (in the aggregate). And after two recessions and two bear markets in less than a decade many aging boomers realize they haven't saved enough to live comfortably in retirement. The solution? Work longer.

Working longer doesn't have to mean we'll stick it out as long as possible with our current employer. We might want to strike out on our own or find part-time employment. We may have no choice but to find a new job after being handed a pink slip. With the passage of time there often comes a desire to find work that gives us greater meaning, allows us to use our talents to improve our community and still earn an income.

But transitions are rarely easy. Yes, we've all heard stories about someone who fled their $30,000-a-year dead-end job and a year later found their inner joy, owning their own rare-vintage vineyard. For the rest of us, even the thought of a major career transitions is daunting. What do I want to do next? The answer is usually hard.

"Career transition has two essential parts,'' writes Marci Alboher, author of the forthcoming "The Encore Handbook: How to Make a Difference in the Second Half of Life.''

"The first is internal, where you do self-assessments and reflection,'' she writes. "The second part is where you test things out in the real world."

Alboher's book is an engaging, practical guide to thinking about transitions for aging boomers. Her insights reflect a number of personal career changes as well as judgments honed from her job at, a San Francisco-based think-tank that concentrates on boomers, work, and social purpose. (Full disclosure: I'm quoted in the book.)

I want to highlight an important theme in the book: The role experimentation plays when contemplating change. We often share a sense that if we're going to make a transition it has to be something big. We have to figure it out and then do it. But there's a telling catchphrase among innovative companies -- enterprises that embrace innovation rather than talk about it. It's "fail early, fail often."

In other words, embrace lots of small experiments. It's how we learn. Alboher suggests strategies ranging from visiting organizations you're intrigued by to taking people out for a coffee to gather information to trying out an internship.

"You can plan, think, and assess yourself to death," she writes. "At some point you just have to get out of your head and into the world.''

I think an experimental mind-set is critical for anyone planning what they want to do during their so-called "encore years.''

What's important is incorporating the experimentation into your retirement planning. The investigation will push you closer to figuring out what it is you really want to do. That may be what you're doing right now, a variation on it, or something very different.

Chris Farrell is economics editor for "Marketplace Money." His e-mail is