I am gasping for breath, looking at a hoop and feebly attempting to bounce a ball when the realisation hits home.

Sweat is pouring from my beetroot coloured head, I’ve got a stitch and my shins hurt. Oxygen would be nice, like a whole canister. And a comfy chair. And a nurse.

I turn to Tom, who isn’t sweating and doesn’t know the meaning of pain.

“I haven’t played basketball for 27 years,” I tell Tom.

Although what actually comes out of my mouth is: “I ... hafn’t ... played ... basket ... err .. basket ... basket-eer-ball for ... umm ... twenty ... twenty ... err ... twenty-seffern yeears ...”

Tom, who is a foot taller than me, just smiles.

“But then I don’t suppose you’re even 27 years old yet,” I say, smiling through the pain, salt water stinging my eyes.

Tom smiles again.

“So how old are you, Tom?” I ask.

“I’m 18.”

Eighteen? “You could be my son,” I think, but don’t say, because Tom might think I’m a weirdo rather than just an old man.

And that’s the realisation. I am too old for this game, this game being basketball.

I look around the hall at the Munrow sports centre and notice it is not just Tom. Everyone is half my age.

I have come along to try a “taster” session of basketball as part of my attempt to get back to something approaching fitness.

The Waynemachine, my fitness guru at the University of Birmingham, suggested trying a session to reinvigorate my self-proclaimed interest in competitive sport.

The Waynemachine, who has been steering me through a work-out regime in the university gym, told me there was no need to become over-competitive. Sport was meant to be fun.

He said this after I pledged to “hit the boards” and “slam dunk those kids off the basketball court.”

If you’re not in it to win it, and inflict physical and emotional pain on your opponent, what’s the point of taking part?

Serena Williams didn’t get to the top of women’s tennis without being a bit of a nutter. Let this be my mantra: I am Serena Williams. I am Serena Williams. I am Serena Williams.”

Sadly, my mental resilience is strong but my flesh is made of weaker stuff. It’s sub-Serena.

After an hour on the basketball court, doing stretching drills, playing a bouncy-ball version of the playground game British Bulldog, lay-ups, dribbling practice and shooting, I was as mobile as Serena’s discarded socks.

Then it was time for ... a game. How could I play a game? I felt like Paula Radcliffe when she pooed herself. I thought of feigning an injury – “Sorry, coach. Bloody hamstring’s gone” – but I’d only be cheating myself.

I was picked for a rotation game in which teams of five compete. The first basket wins, the winning team to stay on.

I was asked who I wanted to “man mark” on the other teams. Now man-marking, I remember, is knackering. It involves running.