Getting old

I am being haunted by the face of an old man.
Let me explain.
I was walking to the shops yesterday when I saw an old man walking slowly and painfully with the aid of a stick. There was something familiar about his face. I walked on a little way, stopped and turned.
It was Frank. Frank the professional rugby player. He used to be a regular at my local many years ago and he was a massive strapping barrel-chested guy who used to talk about the various ways he fouled his opponents on the rugby pitch.
You never shook hands with Frank if you valued the bones in your fingers.
He was vital; robust;loud.
Now he looked about a third the size; like someone had put him in an oven and dried him out. Gaunt face; white hair; sunken cheeks. A parody. A tiny miniscule bit of a human, barely alive. Inching his way along the pavement with a glassy stare and a dying smile. His clothes hung off him.
It was a heart-stopping moment of realisation. I have never been as shocked by the ageing process. I found it truly frightening. More frightening than any horror film. A reminder of my own mortality.
I keep seeing his face in my mind. I still keep saying "No. It can't be"
But it was.