She said staying in work was one way to boost health – but that taking up new activities on retirement was another way to boost the health.
“Staying in work, volunteering or joining a community group can make sure people stay physically and mentally active for longer. The health benefits of this should not be underestimated.”
By 2020, a third of British workers will be aged over 50, estimates show.
More than three quarters of people aged between 50 and pension age are still in active employment, along with 12 per cent of those over pension age, which is 62 for women and 65 for men.
The report will say that while many pensioners enjoy the benefits of retirement, in many it brings feelings of social isolation.
Dame Sally has previously caused controversy with strict advice, counselling drinkers to “do as I do” and think about the risks of cancer before having a glass of wine.
Last month she urged parents to stop children from helping themselves to snacks from the fridge, in a bid to tackle the obesity crisis.
On Monday health watchdogs published advice, saying GPs should encourage widows and divorcees to take up singing and dancing to stave off dementia and stay physically healthy.
The National Institute for Health and Care Excellence (Nice) said more should be done to prevent loneliness in retirement.
The guidance from Nice says family doctors should be told to offer “tailored community-based physical activity programmes” to older people most “at risk of a decline in their independence and well being”.
Research suggests that social isolation increases the risk of dementia, while more active lifestyles have been shown to protect against a host of diseases and the advance of frailty.
The new quality standard from Nice urges doctors to identify those – such as the recently bereaved, divorced or retired – who might lose opportunities to socialise.
It also says GPs should target those who have recently had to give up driving, and those who are caring for others as those who might not be getting the chance to take part in social activities.