It had modest beginnings - thirteen people running round Bushy Park in Middlesex in October 2004.
Nobody could possibly have predicted how the Saturday morning parkrun would take off. Today there are more than 300 events around the UK, with almost 600,000 registered runners.
Many of these events have sprung up in the Anglia region. Five of them are in Suffolk. The Bury St Edmunds one started in June last year and every Saturday, runners of all abilities and ages head to Nowton Park to take part.
Parkrun is paid for by sponsorship. It's free to enter and you register online to get a barcode which you show at the end of your kilometre (3 mile) run. You are then given an official time.
The aim is to get people out enjoying the fresh air and keeping fit.
There are eight parkruns in Essex and nine in Norfolk. It always begins at 9am with a later start in Scotland because of the darker mornings in winter.