ON A WEEKEND morning in the autumn of 2004, 13 runners lined up in a London park for an informal race — unaware they were taking the first steps in what would become a global movement.

Paul Sinton-Hewitt had simple ambitions: to provide a free, weekly 5-kilometre (3.1 mile) run open to anyone.

“I didn’t know who was going to join me on that day,” Sinton-Hewitt said. “I didn’t care how many people came. I would be on the start line every single week for the rest of my life, and I would help people to run.”