Retirement looks different for people already retired than for those who are near retirement but still working, according to the Northwestern Mutual 2014 Planning and Progress Study.

The average age of retirement for those already retired was 59, according to the study. But those still working say they will work until they are 68. Thirty-eight percent of respondents age 60 and older say they will have to work until they are 75 or older before they can retire and 13 percent say they will never be able to retire.

Another 21 percent do not know when they will be able to retire.

“The research suggests that substantial changes in retirement age and lifestyle are on the horizon,” says Northwestern Mutual. “People expect to work longer, but a sizable number will do so by choice rather than necessity.  Others – and there are plenty of them – aren’t as fortunate and don’t feel they’ll have the luxury of choice.”

“Retirement is being redefined from one generation to the next,” said Greg Oberland, Northwestern Mutual president. “For those who have the flexibility and security to choose, many are deciding to continue working, possibly in second careers that are personally meaningful to them. The key is having that flexibility and security.”

Northwestern Mutual says the gap between expectations and experience is evident in the research findings. Only 37 percent of working adults expect they will be happier in retirement than they are now, but 84 percent of retirees say they are happy in retirement, and 60 percent say they are happier now than they were when they were working.

Oberland says those nearing retirement need to plan for the event. Forty-two percent of respondents had not talked to anyone about retirement, the study shows.