I am still not sure why, but in the middle of December I decided to take up running again. When family members asked me what I wanted for Christmas I found myself saying ‘Some running shoes.’ Once they had stopped laughing and could see that I was serious, they all asked the same question: ‘Why?’

‘I don’t know,’ I said. ‘I just know I need to.’

Now the proud owner of some very bouncy blue running shoes, I go for a run around three times a week. There is a marathon route, just over 5k, a short one, 2k and a bit, a nearly-4k one and a nearly-5k one. Mostly I do the nearly-5k one, except for this week when I have been feeling a bit lazy. I go in my cycling gear. I even have an app.

I say ‘take up running again’, because I did, for a time, make running a habit. More than twenty years ago I would go jogging (I can’t bring myself to say ‘train’) with my friend Peter The Actor. He did it, he told me, so stay trim. ‘You never know when Dickie is going to call with a play.’ As always with Peter, there was a lot of nattering invloved. But he was focussed, too. Running with him was the only time I saw him not stop to talk to passersby whom he knew (which felt like everyone.) Round Brockwell Park we would pant, merrily trying to outdo each other with stories of rejection.

Until one day he got serious. ‘The Great West’s coming up,’ he announced, ‘and we’re down for it.’ He would brook no argument against it (the only time I saw this too).

‘How long is it?’ I asked.

‘Just a half.’

‘Half a what?’

‘Marathon,’ he told me, dead-eyed. ‘Sunday we’re off to Battersea!’

‘What, running there?’

‘Well, we’re not going to drive there, are we?’

‘And back?’

‘Of course back.’

And that is when I began to hate running. It wasn’t the puffing, I didn’t mind that. It was the pain. Specifically in my knees. Somewhere on Lavender Hill I lost him and walked the rest of the way home. He rang me later with some news. His wife, a physio, strongly recommended I did not run through pain. As much as I had begun to dread our sessions, I now felt elated. ‘It was probably that school you went to,’ he said. ‘No one had the proper kit in those days.’

‘Yes, probably,’ I murmured, silently punching the air.

I hadn’t hated running at school. I hated that they made it a punishment. Steep and narrow paths, called drungs, treacherous in winter, linked the school campus to all available routes out of it, for fair purposes or foul. If you were caught doing anything a prefect did not like you would be given a drill, three circuits involving two of the steepest drungs, to be completed at 6.30 on a Friday morning.

The other thing I hated about running was that they didn’t teach it to you. Bowling they taught. And rowing. Or being in the front row. But not running. Either you could do it or you couldn’t. Peter was my first and last teacher of the art I had performed all my life and never got to grips with.

‘Run like a trapper, not a crapper,’ he would say. ‘Low slung, kissing the surface, not banging into it. And the other thing is: short steps uphill. Quick and short, like me.’

I had not thought about any of this until, out on my own in the dusk, I watched some swans bobbing on the swollen floodplain a couple of weeks ago. It occurred to me suddenly that no one would be any the wiser if I had stayed at home. No one is making me do this, I thought. No one is thanking me for it either. And that is why I need to do it, to get me out of myself, to give myself the chance to notice whatever comes along.