Data show millions of Americans are already in what social observers call "encore careers" and millions more want to join them. A recent study from MetLife Foundation and Civic Ventures says 9 million Americans between ages 44 and 70 have encore careers, up from 8.4 million in 2008.

According to new research from Civic Ventures, 31 million people ages 44 to 70 want encore careers combining personal meaning, continued income and social impact, but they have trouble making the financial transition.

Civic Ventures helps people explore encore careers, a concept that is gaining importance as life spans expand. The organization released new research suggesting that it takes an average of 18 months to transition from one job to another – a period that often occurs after a retirement or a layoff in the form of a gap year.

Many people dream about launching a second career in a field they have always wanted to try. But the transition into an encore career can be a long and costly process. Most people earn a significantly lower amount of money (43 percent) or no money at all (24 percent) during the transition from one job to the next, according to a recent MetLife Foundation and Civic Ventures survey.

In Australia, the profound change in life expectancy has created a time span of 20 or 30 years between the traditional retirement age of many workers and their old age. Active older Australians need training to prepare them for encore careers. "If the old golden years dream was the freedom from work, the dream of this new wave is the freedom to work," says Marc Freedman, founder and CEO of Civic Ventures.

One of the most obvious sectors for new jobs is health care. And you won't have to become a gerontologist at age 65 to find a position. "There are certain areas in the workplace where having life experiences and having witnessed and lived through some health events yourself is useful," says Marci Alboher, vice president at Civic Ventures.

The late-life career is still a novel concept, says Marci Alboher, author of One Person/Multiple Careers and a vice president at Civic Ventures, a San Francisco-based think tank that promotes socially responsible "encore careers" for boomers. As the idea becomes more familiar, she says, "the less you will feel like a pioneer when you get out there and envision this path for yourself."

Transitioning to an encore career can be a lengthy and expensive process, and more support mechanisms are needed to help post 50s bridge the gap. Four in five people who experienced time with little to no income, reported a gap of six months or more. Civic Ventures is advocating for more short-term, part-time and paid fellowships at nonprofits that lead to encore careers, as well as lobbying for tax-advantaged savings vehicles to help support older workers changing careers.

Boomers don't want to retire all at once, but breaking away from the traditional abrupt end to work is elusive for many, new research shows. Among people ages 44 to 70 interested in downshifting careers, 40 percent say they aren't financially secure enough to do it, according to the research from Civic Ventures and MetLife Foundation. And among those who have shifted to encore careers, more than two-thirds said they earned no money or took a significant pay cut in the transition.

The financial challenges posed by midlife career changes are hampering the plans of millions of people who are interested in encore careers that can put their experience to work for the greater good, according to a study by MetLife Foundation and Civic Ventures.