I was freezing cold the day Neil Laybourn saw a man in a T-shirt sitting on a high ledge on Waterloo Bridge and made a split-second decision that would change both their lives for ever. When you see someone in need, you don't just walk past.

Hundreds of people were doing that in the morning in London. But Laybourn didn't and it turned out the man was thinking of taking his own life. He launched a campaign to find and thank Laybourn for persuading him to go off that ledge. They talk about mental health issues and suicide prevention together.

It has made me more aware of how important it is to put the amount of kindness you have in you out into the world.

What makes us kind? Why are some of us more compassionate than others?

The Kindness Test, a major new study involving more than 60,000 people from over 120 countries, has been looking into these and other questions. It is believed to be the largest public study of kindness ever carried out.

According to the results of a three-part Radio 4 documentary, people who receive, give or even just notice more acts of kindness tend to experience higher levels of wellbeing and life satisfaction.

More than two-thirds of people think the Pandemic has made people nicer, and nearly 60% of people claim to have received an act of kindness in the previous 24 hours.

It is a big part of human nature to be kind, because it is a big part of how we connect with people and how we have relationships.

South Africans spend 67 minutes on July 18, Nelson Mandela’s birthday, on acts of kindness in their communities, to mark the 67 years he fought for social justice and equality.

South Africans spend 67 minutes on July 18, Nelson Mandela’s birthday, on acts of kindness in their communities, to mark the 67 years he fought for social justice and equality. Photograph: Louise Gubb/Corbis/Getty Images

She explains that our desire to be kind is selfish. We have evolved to be kind because it makes us feel good. It shows you that you care about other people. We want to feel good about ourselves and what we do.

The study found that people who believed in benevolence were more likely to give than people who believed in power and achievement.

People who have been told they should be kind are more likely to notice opportunities to be kind.

Women who filled in the study's online questionnaire were more likely to report being kind, receiving kindness and seeing kindness. She says that caring for people and comforting them is seen as a more feminine activity by women.

The use of the #BeKind on social media is a concern for Hammond. We want social media to be a good place. If kindness is weaponised and used to stop people from talking, then that is a worry.

While boys wear slogans like "born to win", messages like "be kind" and " litter young girls" always win. I would hope that boys are being taught to be kind as they grow up.

Paul Dadge helps Davinia Turrell stagger from Edgware Road Tube station after the London bombings of 7 July 2005.

Paul Dadge helps Davinia Turrell stagger from Edgware Road Tube station after the London bombings of 7 July 2005. Photograph: Edmond Terakopian/PA

The study suggests that your personality is the most important factor in determining how kind you are to others. People who scored high on extraversion, openness to new experiences and agreeableness self- reported giving and receiving more kindness, as did people who talk to strangers.

The reason for this may be that people have more confidence in being kind. British people reported that the most common barrier to kindness was the fear that their actions would be misinterpreted. People are more likely to talk to strangers if they are in a group.

When we asked people how they felt, they said warm and happy and grateful and loved and pleased.

The "nicest man in Britain" once spent a year doing a good deed every day to raise money for 45 different charities. It made him aware of the difference that kind words can make to strangers. There will always be people who go and help if someone falls on the street. It has made me one of the people who go and help. Consciously, I now do it.

He says he became that person after a mindset shift where he wanted someone to help him. That makes you think differently about people.

The more you interact with people, the easier it is to be kind.

He once bought coffee for a woman who looked sad in a Costa Coffee shop and invited her to sit with him. She said no one had been kind to her like that in a while, and then poured her heart out to him about her friend, who was really struggling with cancer.

He realized she was wearing a wig and had eyebrows drawn on when she left. He will never forget the impact she had on him.

Talking to strangers makes us feel more connected with each other. It actually does. All of these things are received well by other people. Connection is everything.