Running is a freedom most of us take for granted, even if we don't do it on a regular basis.
But little more than 40 years ago it was a very different story.
Male runners were an eccentric minority, while women were considered too frail to run, and even banned from official events.
Kathrine Switzer and Roger Robinson are two of the sport's early pioneers and are featured prominently in a new film called, Free to Run.
It tells the story of the right to run and how the sport eventually took the world by storm.
Kathrine was the woman who, in 1967, challenged the all-male tradition of the Boston marathon and became the first woman to officially enter and run the event.
And her husband Roger Robinson ran for England and New Zealand at world level, and has set masters marathon records at Boston and New York.
The pair joins Kathryn Ryan to talk about Free to Run which traces the running movement over the past 50 years.