One quarter of people who are planning to retire this year do not feel ready to give up work, research suggested on Wednesday.
Some 24% of people questioned were reluctant retirees, while just 31% said that they are looking forward to ending work, Prudential found.
More than half (57%) of those surveyed said that they would consider working past the state pension age, although most of these people said that they would prefer to carry on part-time rather than having a full-time job.
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Four in 10 of those thinking about working past pension age said that they needed to boost their retirement income - but a similar proportion said that they would be happy to work on because they enjoy it so much.
One in 20 of those considering prolonging their working lives said that they would like to start up their own business while 9% would like to use a hobby to boost their income.
Prudential recently found that nearly one in five Britons planning to retire this year will have outstanding debts, amounting to £31,200 on average.
However, this figure is lower than a year ago as fewer people retire owing money on their mortgages. Rock bottom interest rates have helped many mortgage holders to pay off their loans more quickly than they had expected.
Meanwhile annuity rates, which set the size of someone's retirement income for life, have plunged.
The insurer previously found that this year's retirees expect to have a typical annual income of £15,300, making them around £3,400 a year worse off than workers who retired in 2008.
Stan Russell, Prudential's retirement income expert, said: "In the past, people went from being in full-time employment one day to being retired the next.
"Retirement is much less of an event these days due to flexible working behaviours, and this is reflected in the attitudes of the class of 2013."
More than 1,000 people planning to retire this year took part in the research.
A Department for Work and Pensions (DWP) spokeswoman said: "Reaching state pension age doesn't necessarily mean having to hang up your work shoes.
"With 11 million British people now expected to live to 100, people should have the opportunity to work for longer.
"That's why we abolished the default retirement age - the last bastion in age discrimination."