Workers are returning to their careers, or starting new ones, after age 65. Here's everything you need to know.

Why are so many retirees returning to the workforce?
More than ever, work is where many of us derive our sense of purpose. That doesn't end at age 65. After being retired for only three months, Sue Ellen King returned to work at the University of Florida Health in Jacksonville, Florida, where she had been a critical care nurse and nursing educator for 38 years. The self-proclaimed "failed retiree" is now working part-time in a position created just for her. "It's perfect," she told The New York Times. "I get the ego reinforcement of having people appreciate what I do. And I appreciate the downtime — now that it's not all downtime." Unretirees are not driven by panic: A Rand Corp. survey of unretirees found that 82 percent never thought of their "retirement" as permanent, and had planned to go back to work in some form. With the average life span for those who reach age 64 now stretching all the way to 84 years old, those who reach retirement age still have many potential years of work to go.

So how do you find your next job?
You may already have the job you'll want in retirement, albeit for more hours than you'd like. Enter the phased retirement, which calls for reduced hours in the same industry, or even with the same company. In fact, 64 percent of workers of all ages expect to step back this way rather than retire all at once, according to a recent survey. On the other end of the spectrum, the hunt may span years if unretirees are looking to change gears. Fully transitioning to a new career can take three to five years when you factor in the time it takes to learn the necessary new skills and build relationships with people in a new industry.

Are there online resources?
Yes, there are, and turning to online job resources specifically tailored for post-retirement work — such as Encore.org, RetirementJobs.com, and AARP's jobs board — can help you navigate the lengthy process. Encore.org, for example, is a nonprofit organization that helps Baby Boomers apply their skills and experience to helping their communities. One way it does that is through its fellowship programs, which connect older professionals with high-level nonprofit work. Jonathan Reuman used one such program in New England to land a position coaching top executives of a nonprofit, Horizons for Homeless Children. It was an opportunity, Reuman said, to tap "decades of experience I was fortunate to gain in my career" for a good cause.

What about part-time work?
Job sites geared toward part-timers, temp positions, and gig work can also turn up opportunities that may lead to longer-term work. Fred Dodd tapped Flex Professionals after a corporate restructuring pushed him out of his career as a risk analyst for large banks at age 63. He'd thought about retiring then. "But part of me just wanted to keep working — partly for the money, but more just because I felt I wanted to do more in my career," he said to Morningstar. Flex Professionals, which focuses on matching seasoned pros with companies seeking part-time help, placed him with a small investment advisory firm.

What kinds of jobs should you consider?
The unretired have the advantage of not needing to focus on the earnings potential of whatever jobs they take on, so these older workers gravitate to more meaningful work. And since you are voluntarily putting your skills and experience to good use, you may well have more autonomy and flexibility than your mid-career colleagues. The Rand Corp. survey of the unretired found that two-thirds of retirees who'd come back to the work world were doing meaningful work they enjoyed. Legal work and community service were popular choices, as was teaching — all areas in which older workers might have an opportunity to make their own schedules. One example: Nat Trives, 82, chose this path after retiring in 1997 from his 40-year career in public service as a Santa Monica police officer, an instructor at California State University, Los Angeles, and an administrator at Santa Monica College. He's now teaching a class on current events and world affairs at Emeritus College, a program for older adults at Santa Monica College, and has been active in more than 20 community organizations.

How will returning to work affect you financially?
Earning more money rarely seems like a bad idea, but it can stir up issues for retirees, including penalties when they claim Social Security benefits early. For example, if you've started claiming Social Security before reaching full retirement age (66 or 67, depending on your birth year), your payout is reduced by $1 for every $2 you earn over $17,040 in 2018. However, if you claim your Social Security payments early and then have a particularly high-earning year in your unretirement, that can boost your payout when you reach full retirement age and your benefit is recalculated.