A lovely thing happened the other weekend. I was working in my office at home, when a paper aeroplane came soaring through the air to land nearby. Written on one wing were the words “open this”. Intrigued, I unfolded the aeroplane to find a lovely message from my six-year-old son.

I asked what I had done to deserve this wonderful gift, but there was no reason. My son had just decided to do something kind – and it made my day. It got me thinking about kindness, and what motivates us to do something nice for somebody else.

Of course, there might be selfish motivations. People might do nice things because they think there’s something in it for them. It might help their reputation and social standing, or there might be a financial reward in it for them. Or there might be a sudden emergency and instinct could kick in to help someone in danger…

All of these are completely understandable motives for doing something kind and nice for other people. But what we see in the video clip was that, as one person came to help, so did more and more, until everyone on the train and platform was united in trying to help the single passenger in distress. This domino effect is powerful, and it can happen more slowly and subtly than in the emergency situation we saw on the station platform in Australia.

There are global movements like Random Acts of Kindness and Pay It Forward which are founded on the idea that if each of us acts kindly towards another person for no other reason than that it’s a nice thing – the right thing – to do, it has the cumulative effect of making the world better for all of us. And this is not a new idea!

Marcus Aurelius was Roman Emperor from 161 to 180 AD, and a renowned philosopher in the Stoic school. In his book Meditations, he lays out his guide to self-improvement, including in the twelfth book this simple advice:

If it’s not right, don’t do it

If it’s not true, don’t say it.

This is a great maxim to live by; indeed, if we all stuck to that rule, our world would certainly be a better one. The only thing I take issue with in Marcus Aurelius’ advice is the note of prohibition, of telling us what not to do. I would revise it to:

If it’s right, do it.

If it’s true, say it.

But of course, truth always needs to be tempered with kindness. And, before we act or speak, we need to think carefully about our actions and words.

This came through to me most powerfully this year when I heard the tragic story of Megan Evans. 14-year-old Megan, from Milford Haven was found dead on February 7. She had been the victim of online bullying, which her mother Nicola Harteveld believes drove her to take her own life.

“Megan was bright, vivacious, happy, hugely popular, sporty, confident, outgoing, fiercely independent, just a normal, happy go lucky teenager,” Ms Harteveld told Phillip Schofield and This Morning co-host Holly Willoughby, when she appeared on the show in February.

When Megan started to be inundated with bullying messages on Snapchat, she kept it to herself. Her mother said: “We’re all distraught, and angry because no one noticed anything different with her.”

The final message she received read “Why don’t you kill yourself?”

Megan replied saying: “Ok.”

The fact that somebody in Megan’s life chose to express cruelty and unkindness had the most tragic and devastating consequences. Her family and her friends – and the young person who sent that final message – will be living with the consequences of that for the rest of their lives.

However, it doesn’t have to be that way. In 2007, Jonny Benjamin, aged just 20, was diagnosed with a mental illness, schizophrenia, and hospitalised. Desperate, and unable to understand his condition or see any way out, on January 14th 2008 he walked out of hospital in London and on to Waterloo Bridge, intending to throw himself off into the icy waters below. Hundreds of Londoners were walking across the bridge on their way to work. How many of them saw what was happening? How many walked on? We don’t know. But we do know that one man stopped and spoke to Jonny. He offered to buy him a cup of coffee, and he said words which changed Jonny’s life. He said: “you can get through this. You can get better.”  Up until that moment, nobody had told Jonny that getting better was a possibility. And, in that moment, Jonny himself stepped back from the brink. After twenty five minutes of talking, he came down. The police took him away. And the stranger went on his way to work.

Jonny went on to control his condition with medication and treatment, and became a campaigner for mental health, raising awareness of the condition so that other sufferers have people to tell them “you can get through this; you can get better.” In 2014 he ran a campaign to find the stranger on the bridge who stopped and helped him six years earlier, using social media to track him down. He found him. He is a man called Neil Laybourn, who said this:

“In truth, it could have been anyone who stopped that day. It could have been the person behind me, but this time it was me.”

Neil’s kindness saved Jonny’s life, and Jonny’s life has gone on to save countless others through his campaigning work. He couldn’t have known that at the moment he chose to stop and help; in that moment, he was just doing the right thing because it was the right thing to do.

When we do something nice for no reason, everybody benefits. We feel better; we make somebody else’s life better too. At school this week – and from now on – make sure that you choose kindness. Do something nice for somebody else. Help one another. Not because there’s anything in it for you, but because when you do something kind, you’ve made school a nicer place for someone else to be. And if it’s a nicer place for someone else, it’ll be nicer for you too. So when you choose kindness, everybody benefits.

You can take a “Be Kind” pledge on the This Morning website here, and view some more “kindness” videos below: