In today's CEO Daily, Phil Wahba, writing from New York, examines how chief executives can plan for successful retirements. Elsewhere in the newsletter: Bank of America is worried about bonds, and the markets were mixed as inflation expectations ticked up, along with news and watercooler chat from Fortune.

Earlier this month, Wahba wrote about how more companies—among them Verizon, Boeing and Cracker Barrel—have been hiring CEOs out of retirement, often in times of crisis. The playbook is a familiar one in corporate America: Howard Schultz, for instance, came out of retirement to serve as Starbucks' interim CEO in 2022. But why do these executives, presumably wealthy enough never to work again, accept a grueling new assignment in their sixth or seventh decades? A new study suggests an answer: they simply weren't prepared for retirement.

New data published by Boston Consulting Group (BCG) in early August found that only 40% of former CEOs felt satisfied with their transition from hard-charging chief executive to retiree in the first year after making the move. It seems that many CEOs, like millions of other Americans, underestimate the emotional upheaval that comes from suddenly having a lighter schedule, no longer having a role central to their identity, and no longer having the structure that a job provides. The adjustment is not just a personal matter: how smoothly a departing CEO handles the transition can shape a company's succession planning, and in moments of crisis can leave directors reaching for a proven veteran rather than grooming an insider.

"Is the decision to get a new CEO job really motivated by value creation where you know a unique skill that you bring that only you can do, or is it … really more fear or vanity?" asks Christine Barton, leader of BCG's North America CEO Advisory practice.

The difficulty can be especially acute for CEOs who are still relatively young—in their 50s and 60s—and want to stay in the mix. Mary Dillon, former CEO of Ulta Beauty, told Fortune three years ago that when she came out of retirement after a highly successful stint at Ulta to lead Foot Locker in her early 60s, "I didn't realize how much I would miss having one big thing to focus on and how much I would miss leading a retail company."

There is something companies can do to help: preparing CEOs to leave. Having an executive coach is pretty standard now, but Barton says a growing niche within the CEO coaching world is specifically tailored to helping executives prepare for active retirement and build their legacy.

The survey, which covered former CEOs of companies with at least $1 billion in revenue, found that three to four meaningful activities—such as serving on a board, being an advisor, or teaching—were the sweet spot where a retiree can still feel needed and useful without becoming overprogrammed.

Once again, self-awareness is key. "The portfolio career can be incredibly exciting, but it has to be intentional, and you have to do real self-reflection on whether or not you're at that stage," says Barton.

The BCG report found that after one year, 90% of CEOs were happy with how things went with their retirement. But Barton points to one sure fix for companies that would otherwise have to lure a CEO back from retirement: focus on building a robust internal pipeline now, long before the leader is ready to leave.

CEO Daily can be contacted via Diane Brady at diane.brady@fortune.com.

This story was originally featured on Fortune.com.