Nyambe Ikasaya, 38, no longer wants to be called a personal trainer. He floats “fitness and wellbeing facilitator”, and I tell him I’ll think of something better. (Gyms make me obnoxiously dominant. I can’t win a squat-off, but I can pour scorn on words like “facilitator”.) The blood tests, the hypoxic chamber, those results are all on their way: I’m having a full-body MOT and this is just phase one, the bit where they check your wing mirrors and make sure you’re not two cars welded together. Nyambe attaches some pads to my hand and foot. “It’s a tiny electric pulse, you won’t feel it,” he says, which I don’t believe but turns out to be true.

My results are incredible: 15% fat, 85% lean, 0.2% Wonder Woman. My metabolic rate is such that I can burn 1,552 calories a day without even getting out of bed. Nyambe looks at me with calm bemusement. He shimmers with good health, yet it turns out I am fitter than him. “I’ve sometimes been in situations,” he says slowly, “where a person hasn’t got their height exactly right, so I’m just going to check that.” Huh. I was out by 15cm. Damned metric system. At 174cm, my numbers make more sense: 33.4 litres of body water, which is normal, 23% fat. My fitness goal, according to Nyambe, should be to gain 4kg of solid muscle.

Mine is the scrawny, crow-like version of middle age, which doesn’t get enough sympathy, because weight loss gets all the attention. Dusty, obsolete muscles, unused since the 90s, like a Nokia in a cutlery drawer. I have the body of a person who’s been sitting still for decades, hunched forward, jabbing her chin at imaginary enemies. I have an overly strong anterior aspect (front muscles), compensating for a weak posterior one; Nyambe can tell this just by looking at me. When you move your legs, your muscles should engage in a particular order: hamstring, glutes, lower back. My glutes barely engage at all; my arse quite literally can’t be arsed.

I do five and a half press-ups like a weakling in the opening shot of a prison movie. I can do a wall sit (back against a wall, sat on an imaginary chair until your thighs catch fire) for 72 seconds, which Nyambe says is “fair”. He prescribes squats, planks, sit-ups, push-ups, wall sits, and aerobic exercise for cardio fitness, without which you won’t have the energy for the rest. Two hours a week should do it.

There’s no mystery to it, Nyambe says, bodies are designed to move. Maybe I’ll move mine then. “Fitness and wellbeing inspirer!” I announce, triumphantly.