One study in France even suggested that working longer can lower the risk of developing dementia.
The irony is that the dream of early retirement on the golf course was marketed to executives in the 1970s, just at the time when life expectancy at 65 had started to rise because people were giving up smoking. Of today's 65-year-olds, some will have 30 more years to go.
An institutional pension age can fix in our heads (and those of our employers) the idea that we are washed up at 65, which is at odds with the fact that one in four Brits and two in five Americans, are now "unretiring".
Different experiences across the world suggest that working longer is feasible: 84 per cent of 55- to 64-year-olds are still working in Iceland, 78 per cent in New Zealand and 76 per cent in Sweden. The UK trails at 64 per cent. If the UK in 2017 had matched the older workers' employment rate of New Zealand, according to analysis by PwC, it could have added almost 9 per cent to its gross domestic product.
But it's not always easy to find a job after 55, let alone at 70. Countries with higher employment rates for older workers have often invested in teaching digital skills, something employers fear older workers lack.
Some also have more comprehensive state care systems which mean fewer people struggle to combine work with caring for elderly relatives. In Sweden, 8 per cent of adults are working as informal carers, compared with 15 per cent in the UK.
Not everyone benefits from working longer, especially if their job is repetitive and stressful. Nor is it fair to ask everyone to work to 75, given the growing gaps in healthy life expectancy between different income groups. People living in the South East of England, for example, are likely to enjoy eight more years of life free from disability than those living in the poorer North East.
There's another problem: the people who may find work most easily in their seventies are professionals with good qualifications helped by organisations such as Encore, which matches retirees to non-profits. But the people who most need state pensions are the ones who have spent their lives in low-paid, insecure jobs that get harder to come by, especially if they're physically demanding.
Pension ages should certainly keep pace with average life expectancy. But to postpone the pension age further would require a revolution in employer attitudes, and effective lifelong learning to help people re-energise and reskill. Singapore's inspiring Skills Future programme gives a voucher to every citizen to spend on a vast array of approved training courses with no upper age limit. However, it's very expensive.
Other countries could start by prioritising groups who didn't do well at school the first time round and who don't have the requisite networks to find another job later in life. I'm thinking of care workers in particular — often women — whose interpersonal skills are becoming more important as artificial intelligence takes over many cognitive tasks. But we are not good at teaching such emotional intelligence, nor at helping people who have it move up the employment ladder. The best way to learn is often on the job: but few companies are keen to train people over 50.
The UK government is not about to raise the pension age any time soon. But the CSJ has done us a service if it starts to change the way we all think about retirement. Why should judges retire at 70, just when they are starting to become wise? Why should university professors continue to inspire students into their 80s but business executives be put out to pasture at 65?
As we approach the fourth industrial revolution, it's often assumed that robots will displace humans and that the oldest of our species should make way for the younger generation.
In reality, however, retiring baby boomers and falling birth rates in many countries are throwing up skills shortages. Some companies already retain the wisdom and institutional memory of older workers by offering them part-time roles outside of line management. But it should also be acceptable to start again and take on new challenges.
De Niro's character was on an intern programme for senior citizens. As far as I know, no such programme exists in real life. Perhaps it should.
Written by: Camilla Cavendish
© Financial Times