In a lot of ways, I feel bad for people who decided they hated unnecessary physical exertion during PE lessons and have given it a studied miss ever since. But in one important way, I don’t: if you avoid picking up a barbell or lacing up a pair of running shoes until hitting middle age, you could roll into your late 40s faster and stronger than you have ever been. Whereas – and don’t feel too sorry for me, because I’m going to start showing off in a minute – at 44, the best way to describe my gym regime is probably “managed decline”.

Let’s get the showing-off out of the way first. In my 30s – I didn’t actually start going to the gym myself until I was 29 – I could do a squat with double my own bodyweight on my back, and run 5km in a shade over 21 minutes. I could pull a small van and do a no-handed (AKA aerial) cartwheel. I could, and I’m not exaggerating, hoist a Vauxhall Astra hatchback off the ground 11 times in 90 seconds. I did just that in a competition.

But nothing lasts for ever, and at some point you have to accept that the personal bests column in your workout spreadsheet is probably frozen for good. You get an injury, or you back off a bit, and the weight you once did as a warmup starts to feel quite heavy, then like an actual challenge, then like a forlorn hope. You don’t ever regret lifting it in the first place – as Socrates once nearly wrote, it is a disgrace to grow old without seeing how jacked you can get – but your best Instagram posts now come with a light filter of sadness.

So how to cope? Well, for me, the solution turned out to be pretty simple: stop doing the exercises you are most emotionally invested in. For anyone who has dabbled with getting really strong, for instance, the deadlift, bench press and back squat all come with an extra few kilos of mental baggage – they’re the Big Three, the ones you do in competition and the ones everyone else asks about, so you spend more time than is probably healthy thinking about how to make them go up a tiny bit.

Here’s the trick, though, dear reader: you can simply not bother with them any more. These days, I do kettlebell swings instead of deadlifts, and unweighted squats instead of weighted ones. I haven’t done any bench pressing in about two years: press-ups are more fun, less equipment-intensive, and less likely to make something in my shoulder go ping. And because there’s no real frame of reference for any of this stuff, I couldn’t care less about my PBs in any of it: I can simply biff out a couple of decent workouts a week, not really noticing that I’m getting fractionally weaker year on year.

Anecdotally, a lot of runners do something similar: I know at least two ultra athletes who started on the longer distances because they were sick of everyone asking about their times over the shorter ones. Tell a non-runner you have done a sub-four-hour marathon and they want to know where that puts you on the performance bell curve. Tell them you have run 40 miles in one go and they’re impressed that you managed it at all.

Lifting weights is quite often a sort of microcosm for practising larger life skills – persistence, planning, getting up early when you don’t want to – and this experience, I hope, has given me a framework for thinking about getting older more generally. I did a lot of things in my youth that I simply can’t manage any more – going to festivals, staying out until 2am on a work night, pretending to “get” experimental metal – and rather than mourning these, or trying to cling to them as they go away, I’ve simply replaced them with other stuff. Hopefully, this will be something I do for the rest of my life: finding new joy in jazz, cryptic crosswords and wood-carving as my old interests fade like workouts on a whiteboard. As for the physical stuff, I feel pretty privileged to have worked out most of the things my body was capable of before my testosterone levels peaked and the knee injuries began. Socrates was right about one thing, though: I should have tried taekwondo.

• Joel Snape is a writer and fitness expert