Not stopping to remove her coat or to say hello, the boy’s mother entered the room and strode towards me. She grabbed me by each elbow and looked me square in the eye.

“He’s eating fruit.”

There can be few schools in the country that do not in some way attempt to promote healthy eating among their pupils. Queues snaking out of nearby fried chicken shops and convenience stores give an indication as to how uphill a task this is.

The parent in question had been beating the drum at home for years, with little success. Now, suddenly, her son was eating fruit. Voluntarily.

What had caused the change?

Her son had been taught better impulse control. And further, he had been supported in using those skills every day.

It was part of a school-wide effort to make the teaching of impulse control in our school a priority. The skills our students learned helped them take better care of their health and wellbeing, and also increased their concentration during class and homework tasks, as well as their motivation and their confidence, as they tackled their GCSEs.

So why don’t we explicitly teach impulse control and support it in every school?

Every week we see stories in the media about another thing on which schools must take action for the welfare of their pupils.

Drugs, alcohol, self-harming, safety on the internet, exam anxiety, bullying...teachers could be forgiven if they felt overwhelmed.

At present, the response largely consists of an attempt to inform children and parents - to suggest solutions to arm them with the knowledge that might help them address the problem. Visiting speakers bring expertise and often personal insight. PSHE programmes are increasingly prevalent.

This is important work and must continue. But while it is necessary, it is not sufficient.

A child may be less likely to share a photo online if they have been made aware of the risks involved. But the impulse to hit “send” will likely remain - and has to be resisted.

Similarly, in the confrontation at the bus stop, the punch has to stay unthrown. At the party, the proffered drink or substance must be refused. Peer pressure weighs heavily on every human, but never more so than in our teenage years. Our pupils often find themselves behaving in ways they know they should not - in ways that they, outside the moment at least, would rather they did not.

Fear the waking dread

And then there are the countless little battles fought daily by pupils against their own natural inclination to procrastinate, lose focus or self-belief. Often imperceptible, in real time at least, to teachers and parents, they have huge eventual consequences for attainment.

“Scared Straight” programmes, which have run in the US for 40 years, originated from the common sense premise that if children and young adults were equipped with first-hand knowledge of how terrible life in prison was, they would be less likely to offend. But multiple studies have found that, if anything, participants’ chances of returning to jail as inmates rather than visitors are increased, rather than reduced.

Similarly, our efforts to scare pupils into avoiding temptation often end up with unsuccessful outcomes.

So why don’t we try a different tack?

The solution has to be to explicitly teach impulse control in its own standalone time. Pupils need opportunities to learn why their inclinations will often be counter to their long-term interests - and accrue practical techniques to resist those inclinations. They also need the school to provide a structure in which they can practice those techniques.

We are talking about metacognition - the act of thinking about thinking. Long accepted as vital by many in professional sport - and increasingly prevalent in business and the arts - it has always formed part of the discourse of day-to-day life. Phrases such as “look on the bright side” and “pull yourself together” pertain to thought and how it may have a positive effect on our behaviour.

As the research of Walter Mischel, author of The Marshmallow Test, demonstrates, metacognitive processes can increase the ability to exercise impulse control.

Our instincts so often run contrary to our wellbeing because while today, we are concerned with the next 10 years, our ancestors’ priority was the next 10 minutes. Procrastination and a desire to gorge made perfect sense then, but the rules have changed.

Some people do develop metacognitive processes by themselves, through trial and error. However, we can both accelerate their progression in this - and initiate it for others - by giving allocated time and guidance. How to plan for lessons, homework, revision and exams, how to reflect with appropriate positive weighting to both build confidence and identify areas for improvement and how to design then direct their attention to helpful thoughts of their choosing in situations where unhelpful ones have arisen previously.

If they are to become habits, these processes must be carefully designed to be both speedy and worthwhile. We should no more presume that pupils will work these out for themselves as they go along than we do that they will happen upon a method for solving simultaneous equations.

If a Year 7 pupil learns these skills, they then have up to 1,365 school days in which to develop them. Schools are rarely time-rich. However, the best examples of practice that I have seen have been where the process of sitting down and writing plans and reflections has taken place in morning and afternoon registration. In many schools, this is viewed by many pupils and even some teachers as dead time. All the more exciting, then, to see it used by even very young children to plan their day, see challenges coming and rise to meet them.

The act of writing is key. It creates focus on sleep, diet, exercise, the day ahead and the day just gone, things that we all agree are important but so often get lost in the tumult of a school day. And with maybe 2,730 opportunities to practise this focus, the potential for improvement is huge.

Here’s an example exercise from a tutor time:

Aim: Be asleep by 9.30pm.

* Plan 1: Be in bed with my book and a glass of water by 9pm.

* Plan 2: Plug my phone into a socket in the kitchen at 8pm; leave it there until morning.

* Plan 3: Drink water instead of cola or energy drinks throughout the day.

The real-world successes I have seen have come for a varied range of young people. Quantitative data collected has been highly positive but difficult to strip of confounding variables. However, when combined with testimony from participants, the case looks very strong.

The boy who ate fruit was an aspiring professional sportsman. He knew he should be eating more healthily, he knew it would be sensible to pack his bag the night before a game, he knew he still need to work towards his GCSEs - and yet he had previously failed to get himself to do these things. Once he was in the process of planning and reflecting every school day, he became better at overcoming his unhelpful impulses.

A girl who previously had sat for hours at her desk at home staring at her textbooks, worrying rather than learning, developed physical exercise routines that were incorporated into her revision schedule - and focus words and pictures to use when she felt her anxiety rising. She commented to me on returning from her Easter holidays her surprise on “how not stressed” she was.

Both those young people have now left school and are now forging ahead in their chosen careers.

Impulse control through metacognition is the ultimate transferable skill, as applicable in adult life as it is for that of our children. Its employment will not eliminate the wellbeing issues young people face, any more than toothbrushes have made dentists redundant. But we can reasonably expect it to both reduce the prevalence and severity of harm, allowing those still facing serious problems to receive more time and attention from teachers and other professionals.

Andrew Foster is head of education at Tougher Minds. He tweets @AFosterTeach