JEFF CORBETT: The shock of turning 65

I still don't. And I still never think I'll be old, although I'll admit to a wee shock whenever I see a photo of me. Looking in the mirror doesn't produce the same recoil.

My mother, who can be described fairly as elderly, tells me there is nothing good about being old, and I wonder if the fact that she is old, and in my mind always has been, allows me to be not old.

When she goes, and she told me recently that she won't live forever and she doesn't want to, I expect I will be instantly old. The next cab off the rank has to be old.

I'm reminded of what I never thought would happen whenever I see an old photograph of an instant in my life. A photograph of wife and me with our small children, and I'll have a mini moment of surprise that I never thought they'd grow up, that they wouldn't be small forever, or at least that my wife and I would not always have small children. They did seem to arrive with alarming frequency.

We have two small children now, grandchildren, which is definitely the best way to have small children, and I never thought I'd have grandchildren.

Not that I ever actively thought my small children would not grow to adulthood, or that I would not have grandchildren.

Read more: Why Return and Earn falls short

It seems to be that I never envisaged my circumstances changing, and that may be because circumstances in my life seem to last forever. School, for example, was for me so endlessly tedious that I could never imagine it coming to an end.

Little things, big things. I never thought I would not be able to run flat out, and I don't know when it came to be that I could not.

I never thought that my gloriously free single days would end, and when I was married I never thought I would not be top dog.

I never thought I would be without a mortgage, that I would not have to go to work.

In hindsight I divide my life into segments, each segment defined by my general circumstances, and I don't seem to have entertained the possibility that at any point in time I was merely in the most recent segment, that sooner than I could ever believe that particular segment would come to an end. High school, for example, was interminable yet it was just six years.

Read more: A window into retail worlds

It is one of life's cruelties that time accelerates as we deplete it. Six years had no end when I was a teenager, and I suppose it was a half to a third of my life to that point, while now six years flashes by, when it is probably a half to a third of the life I have left. I've never thought of this segment of my life coming to an end, mind you.

This aversion to recognising that a life's segment will end may explain my, and perhaps your, willingness to believe that bad things happen to other people.

As a smoker many years ago I never thought I would get cancer, and I expect that the great many other smokers never thought the same thing. Part of the trauma of my cancer diagnosis years ago was that I had never thought there would be such a day.

The end of even a segment within a segment can be a shock. For almost 20 years my family would go each year to a camping ground on the mid-north coast for a few weeks after Christmas, and the event became a highlight of our family's year, the other regular campers and the campground owners became part of our network of good friends even if we saw some of them for only that part of the year.

There were changes. One or two died, some couples split and found new lives, some took to travelling overseas, but the event and the group had a life of its own.

Then, one year, what had been unimaginable was reality. No one turned up, for all sorts of reasons, and there were no shared dinners, no afternoon drinks, no laughs and lazy days together, the group was no more, ever again. It was brutally sudden and I hadn't seen it coming.

I never see it coming.

I never thought, I said to my wife when she turned 60, that I'd be sleeping with a 60-year-old woman. Don't worry, she said, you won't be, and I didn't see that coming. I kept my mouth shut when she turned 65 this year.