Boxing is good for you.

Whether you are 15 years old or 50, the basic training required for boxing - a process that Joyce Carol Oates called "the fanatic subordination of the self" - will make you infinitely fitter than you have ever been in your life.

You can't box without getting fit just as you can't swim without getting wet. You can't punch anything for three minutes - heavy bag, speedball, pads, let alone another human being - without a good level of cardiovascular fitness. Nothing pumps the heart and moves the blood and unclogs the veins like boxing.

And you can't take a stiff dig to the belly if all you have down there is a soft gut full of premium lager. Boxing knows endless varieties of sit-ups, and you will do as much abdominal work for boxing as you will in any yoga or Pilates class. Boxing kills your beer belly and awakens your abs.

You have to commit to boxing. You can't do it when the mood takes you. Boxing is not like skiing or scuba diving - it is not something you can do once a year on holiday. Boxing is not even like football or tennis - you can't do it on the odd sunny day in the park. Boxing - even at the strictly amateur, recreational level - requires dedication, discipline and grit.

You can't box without getting fit just as you can't swim without getting wet

And here is what is special about boxing training - your physical fitness is just the start. Boxing is really about your mental fitness. Because boxing makes you calmer. Boxing teaches you control. Boxing heals your head. Boxing engenders respect - for others and for yourself. Boxing gyms often attract wild boys, bad lads, aggressive men - but they all learn, probably in their very first lesson, that you simply can't box without self-control.

Boxing changes a man.

And if they taught boxing in our schools, then boxing could change the world.

What can save the damaged children of the internet? Every older generation always despairs about the younger generation. But in our obese, porn- saturated digital age, a little despair seems in order.

The youth of today are doomed - grown fat on junk food and years spent on their behinds, rendered stupid by their beeping smartphones, their sexuality neutered and twisted by a steady diet of hard-core porn.

What can save them? Only boxing.

Only boxing can toughen them up, only boxing can put them back in the physical world, only boxing can remind them that they have a body, containing a head and a heart, and only boxing can make them beautiful and find them a girlfriend.

Those poor, useless kids! Allegedly more connected to the world than any generation in human history, and yet hopelessly disconnected from the world of muscle and blood. Young people do not carry knives because they are tough. Young people carry knives because they are weak, because they are scared, because they are

­terrified. Because they don't box. If they taught boxing in schools, all of this - the obesity, the porn addiction, the nervous knives - would vanish overnight.

© PA Photos

Boxing was once taught in British state schools. Contrary to what you might think, it was never ­actually banned, but simply died out around the time of the Beatles' first LP.

Boxing was never outlawed in British schools, despite the best efforts of a physician and Labour MP called Edith Summerskill, whose anti-boxing campaign in the late Fifties and early Sixties won widespread support but lost several votes in the House of Commons. The votes may have gone against Summerskill, but the spirit of the age was with her all the way. The times were changing. Memories of the war were fading. National Service had ended. The manly virtues were going out of style. Many people believed that boxing in schools was a relic of our more violent past.

Boxing stopped being taught at school in 1962. Although the Department of Education does not specify what sports should be taught as part of the national curriculum, if a boy wanted to learn to box after 1962, then he had to join a boxing club - thus ensuring that boxing was only taught to boys who were already sporty, aggressive and unafraid. The boys who needed it the least. "Schools are free to offer boxing if they choose," a Department of Education spokeswoman told the BBC. "They should of course bear in mind the safety precautions that should be in place. Generally we ­consider boxing to be best offered through boxing clubs with qualified boxing coaches."

Boxing can't help but restore some sense of common humanity between boys and girls

This has been the general consensus - boxing is just too violent to be taught in schools. The prejudice stems from the image of boxing as the sport of thugs. Novelist and amateur boxer George Garrett disputed that image: "Many good and experienced fighters become gentle and kind people. They have the habit of leaving all their fight in the ring."

This is a golden age for British boxing. Professional boxing has a world champion in Carl Froch, amateur boxing had a revelatory London Olympics, and the clubs of the ABAE - Amateur Boxing Association of England - are booming. But by exiling boxing from schools, it is rendered a minority sport - when it should be in the mainstream. Boxing is the martial art of the West, as integral to our sports culture as kung fu in China, karate and judo in Japan and taekwondo in Korea. There is nothing remotely esoteric about knowing how to defend yourself.

A few years ago schools in Bromley, south London, started introducing boxing training into PE lessons, under the supervision of the ABAE, and although the training was non-contact - they did boxing training but did not spar - the boys and girls were invariably transformed. They always are!

What happens when kids box? Fat kids lose weight. Bullies learn humility. Girls are empowered. The weak become stronger. The timid find courage. The wild kids learn control. The unhealthy get fit.

And everybody learns that boxing has no room for anger.

The ABAE's Whole Sport Plan aims to increase participation in schools, broadening the opportunities for kids to try boxing for the first time and then join a club. This is a worthy aim. But boxing should be as much a part of double games as football. The sniffy disdain of the Establishment towards boxing is because they assume that boxing in schools would be a blood bath. But no responsible boxing trainer would let a student spar until he has mastered the fundamentals of defending himself - blocking, slipping, ducking, running.

Because of its necessary obsession with weight, and matching like with like, boxing is evenly contested like no other sport.

There is no such thing as a "fair Formula One race" or a "fair football match". But the concept of a fair fight is integral to boxing. This is one of the reasons why, statistically speaking, boxing is a relatively safe sport. Boxers are not thrill-seekers. I have sparred for years but I would not dream of riding a bicycle in London traffic. Now that's what I call scary.

It is true that professional boxers take blows to the head that would very easily concuss or kill an ordinary man. But amateur boxers, recreational boxers - and even professionals sparring in the gym before a big fight - always wear a headguard. You get the odd black eye or bloody nose, but recreational boxers are never going to end up seriously damaged because we are not being hit by Joe Frazier, and because we are wearing those headguards and, most importantly of all, because we are not fighting beyond the point of extreme dehydration - the death zone where most serious boxing injuries occur.

Boxing teaches you to defend yourself at all times. Boxing teaches you that there are as many ways to avoid a punch as there are to throw one. And although the state schools gave up teaching boxing in 1962, in the great private schools they never stopped believing in the healing power of boxing. And that is why the only men I know who boxed at school all went to Eton.

In an age when a generation of lost boys are having their attitude to women warped by violent, woman-hating porn, when they spend their leisure hours playing with their mouse until it squeaks, boxing can't help but restore some sense of common humanity between boys and girls. As we saw at the London 2012 Olympics - girls can box. And they can do it brilliantly.

London 2012 radically changed attitudes to women's boxing that had persisted for generations. This wasn't women's football or women's tennis - a poor substitute for the real thing. This was two-fisted, high-octane entertainment from the likes of the UK's Nicola Adams and Ireland's Katie Taylor. When Amir Khan won his silver medal at Athens 2004, he said, "Deep down I think women shouldn't fight. That's my opinion. When you get hit it can be very painful. Women can get knocked out."

Oh, Amir! Pot. Kettle. Black. By London 2012, Khan was enjoying the women's boxing in the company of the prime minister. "Wow, the girls were unbelievable," Lennox Lewis said, while the Daily Telegraph picked women's boxing as "the purest distillation of the Olympic spirit - sport for sport's sake".

Nothing revealed the inclusive nature of the sport like the female boxers of London 2012. Boxing is not for the big and hard, or for boys and men, or even for the particularly athletic or the tough. Boxing is for everyone.

It scarcely seems conceivable that women's boxing was not an Olympic sport before London 2012. As recently as 1996, women's boxing was banned in the UK, as recently as 1998 women were denied a boxing licence on the grounds that premenstrual syndrome made them unstable. Not like all those well-balanced male boxers such as Mike Tyson.

© PA Photos

Footballers bicker, swear, spit and bitch-slap each other in the tunnel. But it is almost unknown for boxers to do anything after a fight other than warmly embrace. Boxing has a bad reputation.

Traditionally boxing has been a sanctuary for bad lads. But boxing saves anybody who embraces it. Because what boxing teaches you is that there is good stuff inside you.

Boxing is not about being a tough guy. It is about being a better man. For ultimately boxing is not about how hard you can hit - it is about how hard you can get hit and still carry on. And because boxing demands so much, because boxing asks for that fanatic subordination of the self - even of the overweight kid who shyly gives the training a try for the first time, even of the middle-aged man who has not been in a fight for 30 years - in return, boxing gives you treasure to carry with you through a lifetime.

And when life hits you hard - when you lose your job, or lose your girl, or lose your health - you might find that you have a thread of steel inside you, and it will make those hard times more bearable.

Where did that thread of steel come from? It came from the sit-ups you did when your sides were on fire. It came from the medicine ball that you held up when your arms wanted to rest. It came from the hard knocks you took, and the sweat you left in the gym, and the way you learned to bite down on your gumshield and stick out your weary jab when a lesser man would have caved in. In your darkest hours, you will discover that you are a better man than you ever knew.

And it will be because you boxed.

Originally published in the September 2013 edition of British GQ.