After Mr Chip Conley sold Joie de Vivre, the boutique hotel company he created and ran for about 24 years, his life took an unexpected turn.

At 52, he was sought out by Mr Brian Chesky, the then-31-year-old chief executive of Airbnb, for advice on how to turn the fledgling home-sharing start-up into a major player in the hospitality field.

For the next four years, Mr Conley worked at Airbnb, toggling between being a mentor and an intern in a sometimes baffling new role - a "modern elder", as he put it.

As a veteran hospitality executive, he was used to being the "sage on the stage".

But as a newbie in the tech sector, he was often the oldest person in the room, learning from colleagues who were young enough to be his children.

In a new book, Wisdom At Work, he writes that everyone working past middle age today needs to become a modern elder, simultaneously sharing wisdom while embracing fresh ideas and ways of thinking.

I think he is on to something.

It used to be, 50 was a time to begin thinking about retirement. But today, many people in their 50s - myself included - plan to work two or three more decades.

To become modern elders, we have to find new ways to stay relevant and keep our minds open, skills fresh and humility intact.

Some did their homework and went back to school for jobs where there are known shortages - like nursing or teaching in fields such as science and technology. Some found their way through volunteering or attending specialised fellowships or boot camps. Others teamed up with younger partners to lead new ventures. Most, it seems, did a combination of all these things.

Ms Sharon Lewis, an independent consultant on consumer habits, was doing scouting work for the cultural forecasting firm sparks & honey when she heard about the company's new cultural apprentice programme.

The apprenticeship was designed to bring together millennials and people with 30 years of professional experience to work on, among other things, a report on the future of work.

Ms Lewis decided to sign up for the 16-week programme, which offered only a modest stipend, as a 60th-birthday present to herself.

"The idea of working around so many younger people was exciting and invigorating," she said. "I feel wiser, more well-rounded and updated, and I'm almost in withdrawal now."

She especially appreciated the mutual mentoring. "We're not competing with one another because we're at different life stages."

Despite the promising stories, I hear a lot from people over 50, even over 45, who are doing the right things but still not finding successful midlife transitions. Ageism is rampant - and internalised, with midlifers questioning our own ability to succeed in a world where youth is prized.

And while there are many new offerings to help people make late-career transitions, moving into an encore career still requires an immense amount of creativity and persistence.

I have learnt two things from my interviews about making these transitions easier.

First, and most obviously, it helps to have a financial safety net. So volunteering or refreshing skills while still employed, collecting severance or a pension, or having a partner who provides an income or health insurance can make a big difference. It is far more daunting without that kind of cushion.

Second, the attitudes of younger colleagues are just as important as our own when we think about finding new roles in a rapidly transforming workplace.

NYTIMES

•The writer is the vice-president for strategic communications at Encore.org.