The Great Recession served up some nasty financial surprises to people approaching retirement - the housing crash, job loss and shrunken 401(k)s, for starters.

But retirement can bring lifestyle surprises, too. It's one of life's biggest transitions, and a major leap into the unknown. Hoping to lessen the guesswork for people who aren't there yet, I asked experts who work with people transitioning to retirement about the surprises they hear about most often.

"Time freedom" is a shock for many, says Richard Leider, an executive career coach and co-author of "Life Reimagined: Discovering Your New Life Possibilities" (Berrett-Koehler Publishers, 2013).

"Without the time structure of working, folks often go on autopilot, the default position of repeating old patterns," he says. "However, there is no status in the status quo. So, at about the one-year mark, they realize that time is their most precious currency. Often a wake-up call - health, relationships, money or caregiving - forces reflection and helps them to say 'no' to the less important things that simply clutter up a life and 'yes' to the more important things that define a purposeful life. They choose fulfilling time."

Wealth psychology expert Kathleen Burns Kingsbury also sees people struggling to structure their new lives. "One of the biggest surprises retirees face is the adjustment to not working full-time," says Kingsbury, author of "How to Give Financial Advice to Couples" (McGraw-Hill, 2013). "While people typically fantasize about what life will be like without a job, the reality is sometimes it's a bit of a shock to the system.

"Work provides structure, social connections and a sense of purpose. It is important for pre-retirees who are not going to work in retirement to consider how they will meet these needs outside of a work environment," she adds.

Sometimes, that leads to greater spirituality, says Carol Orsborn, editor-in-chief of FiercewithAge.com and author of 21 books about the baby boomer generation.

"The heightened search for meaning in the face of mortality comes as no surprise," she says. "The bigger surprise is that as it turns out, many of the things we most fear - loss of identity, erosion of ego, increased marginalization - hold the potential to transform aging into a spiritual path.

"Many retirees report that they are achieving levels of fulfillment, peace and joy not despite the things that happen to them as they age, but because of them. This transcends individual experience, with sufficient mass to constitute what is being termed 'the conscious aging movement.' "

Not that there aren't earth-bound worries. "The biggest surprise is about money," says Helen Dennis, a specialist in aging, employment and retirement. "This is true particularly among women who have earned a good income and find that eight or 10 years into retirement, they fear running short and need to change their lifestyle, all within an uncertain economy. Add to this their surprising initial discomfort in spending their retirement income without depositing a work-earned check."

Changing housing needs also can surprise, especially for single retirees. "For single retirees, recognizing that their current home or location no longer 'works' is a common surprise," says Jan Cullinane, author of "The Single Woman's Guide to Retirement" (AARP/John Wiley, 2012). "Upon leaving a primary career, the daily social support built into a job is yanked away. Pairing that with becoming suddenly single through divorce or widowhood, the home that served them well may no longer be appropriate."

For married couples, the surprise might be a desire to get away from one another. "Many retirees end up bored with too much free time and often discover, if they're in a relationship, that they get on each other's nerves and want some space and time apart," says Dorian Mintzer, a coach and co-author of "The Couple's Retirement Puzzle: 10 Must-Have Conversations for Creating an Amazing New Life Together" (Lincoln Street Press, 2012).

"They often haven't thought about the role work played -providing structure, self-esteem, time together and time apart from a partner as well as connection engagement and purpose and meaning. Each partner may experience the transition differently, and they may be 'out of sync' with each other. For example, one may want to travel and the other wants to start an encore career."

I received many more comments about retirement surprises than fit here. You can find thoughts from a broader array of experts on my website ((bit.ly/1wxyf2C).

For more from Mark Miller, see link.reuters.com/qyk97s