If I had said five years ago I would be writing on how the middle-aged and ancient can become healthy — which is what this column will be, incidentally; an intermittently reliable guide on how to turn yourself from a wine-sodden, desk bound, muscleless lard mountain into a reasonably fit person — everyone who knew me would have blinked.

Actually, they would have done more than blink. They would have raised eyebrows. They would have scoffed. They would have stabbed their fingers into my wobbling beer belly and howled with mocking laughter. If you suspect the same cruel response would greet you, then you are my target reader.

The first lesson is you can’t do it all at once. In fact, the odds are you can do next to nothing at once. You are — and forgive me if I am being rude — old, fat, tired, drunk, slow and bleary. You may not be all of the above. You can be young and an alcoholic, or sober and fat. That said, whatever your specific circumstances, you do not move much. You drive to the shops, work, your children’s school, friends’ homes and the pub. If you don’t, you take the train or the bus or get a lift. At work, you sit staring at a screen. At home, you sit staring at a screen. You stare at screens so continuously your phone might as well be a prosthetic implant in your hand.

When you booze you eat and when you eat you booze. As this is an upmarket magazine with classy readers, you probably don’t think of yourself as an gluttonous alcoholic. Nevertheless, “wine o’clock” strikes earlier and the meals grow larger with every passing year.

Public health officials say modern men and women are living in an “obesogenic environment”. By this they mean food and drink are everywhere in a landscape that might have been designed by a malevolent bureaucrat to maximise calories and minimise movement. If you are poor, fast food, fizzy drink and high-strength lager are on tap. If you are wealthy, the buffet and the wine rack take their place.

People in the obesogenic world waste away. The less you exercise, the weaker you become. Your bones, joints and muscles — especially your heart muscles — atrophy. As important as the physical decline are the lies you tell yourself. News editors know what they are doing when they promote stories saying red wine and red meat are good for you. Readers want to hear that inconvenient facts aren’t facts at all. I certainly did.

My mind was biased towards believing stories that said I wasn’t hurting myself or shortening my life as surely as the minds of supporters and opponents of Trump or Brexit are biased towards news that confirms their prejudices.

 

My favourite piece of fake news is the oft-repeated story that the Body Mass Index (BMI index) lies. The index is a quick and simple measure of your health that divides your weight by the square of your height. It has been used for nearly a century and labels patients as “obese,” “overweight”, “healthy” or “underweight”. The higher your BMI, the higher your risk of heart disease, high blood pressure, type 2 diabetes, strokes, cancer and so on.

But, says everyone, the index takes no account of muscle mass. It said Usain Bolt was borderline “overweight” when he was the fastest sprinter on earth, so why should we bother with the pseudo-scientific scare stories of health Nazis?

Before we go any further with this column, I therefore want readers to get naked and in front of a mirror, and ask: “Do I look like Usain Bolt?”

If the answer is “yes,” stop reading now.

If it’s “um, not really”, you need to understand that psychologically as well as physically you will find improving your life hard. Public health authorities are understandably terrified by the spread of obesity and inability of even the best-funded health services to cope with it.

Their messages, however, fail to explain how difficult exercise is to begin. They adopt an insufferably chirpy tone and assure you anyone can do it. And nearly everyone can. But doctors who turn happy-clappy and tell patients how much “fun” they will have are a disaster. Psychologically, most unfit people begin by thinking exercise is no fun at all and have brains attuned to finding reasons not to do it.

As importantly, most people cannot physically engage in anything except the mildest exercise. Even if somehow they could, say, run 5,000 metres (about three miles) the effort would wreck what muscles they have and they would not be able to move for a week — which would rather defeat the point.

You must begin gradually. In the next issue, I will take you on your first steps by emphasising the truth of the cliché, “You have to walk before you can run.”