A t nine o’clock every Saturday morning, come hail or shine, at a park or public space near you, people are gathering to take part in one of the most astonishing exercise phenomenons of the 21st century. ​Parkrun is breathtaking in its simplicity. You turn up, you run – or jog, or walk – a 5km course. Then you go home. It doesn’t cost you anything, you don’t need the latest expensive kit. But the benefits to your physical health, your mental health and even your local community, are almost immeasurable.

The very first Parkrun took place just over 15 years ago, on 2 October 2004, at Bushy Park in London. Then there were five volunteers and 13 runners. Now there are more than 2,000 Parkrun events taking place in 21 countries. Six million people have registered for the runs, more than half a million have volunteered, and week in, week out there are usually more than 350,000 people lacing up their trainers and pounding the paths at 9 o’clock sharp on Saturday mornings.