I achieved that landmark age of 65 a couple of days ago. Of course, in the future it may not be much of a landmark as in the past. If the UK government continues to push forward the age of retirement - now planned for 66, and maybe 67 - the traditional retirement age of 65 will become meaningless. In fact, I retired from full-time employment when I was 50 and concentrated on writing - and other pursuits. To imagine the last fifteen event-filled years of my life as otherwise being filled with more work along the lines of that which I had been doing up to when I was 50 fills me with horror. Nor can I imagine having to work until I am 67, or even 70, in order to have enough money to retire on. I know, I know, I've been lucky in choosing a career (outside of writing) that gave me a good pension, and that many people aren't so fortunate. But I would hate to have to work for the bulk of my life, and then only have a handful of years to relax or do other things.
As a writer, my long-running characters have aged more or less in line with the timing of the stories. The William Falconer series began in 1994, and that first story was set in 1264. The latest one I am writing is set in 1275, so there has been a slight time-slip, but Falconer is definitely older and more tired than when he began. Will he leave Oxford at last? You will have to wait until the ninth Falconer is published.