Glenn Sutton has run all over the world, pushing his endurance and body to the limits of what's possible.
But the Dunedin man's next challenge has him admitting to being a bit scared.
Starting in two weeks' time, he's going to try and run non-stop from Milford Sound back home to Dunedin, a journey of 617 kilometres.
He tells Mark Leishman what gives him his drive.