Almost a third (31 per cent) believed they could work into their 70s and beyond with one in 14 confident they could keep going into their 80s.
AIG says its independent nationwide study “demonstrates the impact rising life expectancy and health improvements are having as people adapt the way they work and live”.
Longer working lives highlight the support financial protection delivers for individuals and their families, the firm said.
The study showed that, on average, workers believed they will be fit enough to work until 68.
Men were confident they could work until 69, while for women it was slightly lower at 67.
The older people are the longer they believe they will be healthy enough for work – over-55s expect to be able to keep going to nearly 73 compared to around 66 for the under-35s.
Their confidence in being able to continue work backs up changes to the State Pension Age, which is due to be increased to 66 by next year for men and women and 67 between 2026 and 2028 and then to 68 from 2037.
Almost half (47 per cent) of people believe the current average 21 years spent in retirement is just about the right amount of time to spend not working.
But there were a variety of views in the research with around one in seven (14%) adults believing that 21 years of retirement is too long.
In London 28% - twice as many as the UK as a whole believed it was too long.
But one in four (25%) believed 21 years of retirement was not long enough.
AIG Life’s research found on average people expected to live to nearly 82 and to be healthy and active until around 77.3 years of age.
Around one in five (18%) believed they will live past 90 showing the benefits and opportunities that taking a realistic and practical approach to planning ahead financially.
AIG Life believes rising longevity is making it more important for people at all ages to think about the money they might need in life and how they protect their families and their future.
Donald MacLean, chief financial officer at AIG Life, said: “Retirement has changed massively in recent years as improvements in life expectancy and health plus changes in the law mean millions are living longer and can work longer if they want to.
“It is interesting those closest to hitting retirement, the over-55s, are the most confident in retiring later and feel healthy enough on average to keep working into their early 70s.
“Children born today can in many cases expect to live to see their 100th birthday which means people need to consider how they will protect themselves and their families financially in the years to come in case their plans are disrupted by illness.
“Many of us may want to stop work as early as we can while others will be happy to keep working as long as they are physically able to.
“It is clear that we all need to think about what we want, what might happen along the way that could derail that and take practical steps to plan for the future as early as possible.
“Whatever the future we want.”