I have been a member of five gyms in my life – the longest unbroken membership lasting three years, the shortest six months, which I quit and, like a Liz Taylor marriage, rejoined before cancelling for good. I am currently a member of two gyms: one a few streets from my house, which costs $19.99 (£15) a month and offers unlimited bald towel service and a lifeguard always glued to his phone; and one a short bus ride away that, for $120 a month plus extras, is teaching my children to swim.

The latter is part of the YMCA network and, although it’s expensive, it isn’t fancy – it has the vibe of a 1970s leisure centre, with a lot of Bernie Sanders lookalikes harrumphing around in tight shorts – so I feel less guilty about the outlay.

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None of this changes the fact that, except for the children’s swimming classes, I never go to either gym. I don’t talk about going to the gym. It’s not on my to-do list. I no longer have an idea of myself as someone who, given an hour off, might work out. (If I get an hour off I’m either taking a nap or watching a depressing documentary on HBO.) So why can’t I bring myself to cancel?

In years gone by, when I was still forming an image of myself, the possibility that I might be a gym person held itself out with the same promise that came with the purchase of every new dress – that a subtly improved new personality might come with it.

For a while in my 30s, I even saw a personal trainer. Under her guidance, I went around all day doing a weird thing with my shoulder blades that was supposed to improve my core strength. I can’t say I noticed any difference in my well-being but it did make me feel at least open to the possibility of change. Then one day I stopped and never started again.

This changed, for a second, after having kids, when the concept of “me time” took hold like a weed in my brain and I returned to thoughts of the gym. Maybe I could be one of those people who puts even their leisure time to good use – lying in the sauna while working on small-business ideas, or figuring out how better to invest in the stock market.

Anyway, that didn’t happen. On Sunday, after the kids’ swimming lesson at the Y, I swung by the membership desk fully intending to cancel, before putting it off for another week. To be caught out again – I think I am like this, but actually I am like this – seemed at 43 to be vaguely demoralising.

And so I will keep paying, thinking I can turn the ship around, like staying in an unsatisfying relationship because the small defeat in self-knowledge is apparently too much to bear.

Meanwhile the gym is filling up for summer, and the latest round of stomach flu in New York is only half-comically welcomed by women hoping to get thin for the beach. Suddenly this seems like the more honest approach.

• Emma Brockes is a Guardian columnist