When he turned 65, Mario Rebellato was told he had to retire from his job with the British government.
But like an increasing number of people, he decided state retirement age was too young to give up work.
Now, aged 72, he is personal assistant to the managing director of one of London's biggest plumbing firms.
(SOUNDBITE) (English) MARIO REBELLATO, PIMLICO PLUMBERS, SAYING:
"I'm the sort of person who must be productive, all day, every day. I'm due to run my fifth Marathon des Sables. It's quite an endurance marathon - 150 miles across the Moroccan sahara desert."
The number of people in the UK aged over 65 who are still working has doubled in the last 10 years to over a million.
And with health improving, the state pension age set to rise, and returns on retirement savings not being what they once were, that number is only going to grow.
Yves Duhalderborde from Tower Watson says retirement age workers still have plenty to give.
(SOUNDBITE) (English) DR. YVES DUHALDEBORDE, DIRECTOR, TALENT AND REWARDS, TOWERS WATSON, SAYING:
"It's a little bit counterintuitive because people think of older people being slightly slow and so on. Well when you look at statistics they are sick less often, they are less absent than younger workers. So it's really a very reliable part of your workforce."
A recent poll found around 20 per cent of Britons currently working don't plan to retire.
But firms don't seem ready for this.
Another survey of human resources executive showed 59% are not making any progress in this area, while only 50% think their businesses understand the changing needs of older workers.
Either way, workers like Mario aren't prepared to take life easy, anytime soon.