Old age... Imagine an 80-year-old man. Is he sitting in an assisted-living facility, dozing off in front of the TV, legs covered with a blanket? Is he playing soccer with his grandchildren? Or is he chairing a board meeting at a Fortune 500 company?

It's remarkable that, these days, each of these visions is as likely as the others, because people are living for longer and in very different ways. Some of us decline over decades. Others stay fit until the end.

Personal financial insecurity may dictate that people remain in (or return to) the workplace later in life, or it could be a creative passion that keeps them involved. Either way, they're consumers too, equating to a potential $22 trillion market worldwide.

The nuances – and opportunities – of this diverse picture aren't lost on Susan Wilner Golden, a former venture capitalist who now leads a program on the business implications of longevity at Stanford Business School.

She recently brought some of her ideas together in a new book, "Stage (Not Age)." In this clip from my Expert Interview podcast with Susan, she explains what's behind that title.

Breaking Age Stereotypes

Shakespeare wrote of "the seven ages of man." Wilner Golden believes it's more like 18 stages.

Some of them, like caregiving and formal education, may come around a few times in one life. And everyone will experience their stages differently.

"The key is to stop thinking of all older adults as just one type of person," she says. "It's much more important to think about what stage of life they're in. Are they in their repurposed stage, a new renaissance stage?"

Yet the idea that all older people are alike remains stubbornly prevalent in the business world.

"You can look at a lot of advertising and marketing toward older adults. It often portrays people as one type of person, which is frail. Somebody's holding their hand. And that maybe is needed, but that's not true for everybody," she points out.

Opportunities of Age

The "old person" stereotypes may be outdated, but older people still have specific needs, as they move from one stage to another. This is where the business opportunities lie.