Runners as young as seven are taking part in Auckland's marathon this morning.
Leon Cooke is one of the participants in the Kids Marathon, but he's spread the gruelling event over time.
His mum Tania says Leon's been training for 12 weeks, and he's so far covered 40km.
He runs the final 2.195km of the full marathon this morning.
Ms MacKenzie-Cooke says her son really wanted to take part.
"He seemed really dedicated. They have an actual training sheet that you print off, and you tick the days off as you go, and he just loves it.
"So next generation of runners here we go, I guess.''
There will be road closures across Auckland this morning, as the marathon takes over the city's streets.
The south-bound clip-on lane of the Harbour Bridge will be closed for runners, leaving three lanes in each direction for cars.
The off-ramps for Shelly Beach Road and Fanshawe Street and the Curran Street on-ramp northbound will also be closed.
Local roads on the marathon route, through the North Shore and central city, will also be impacted.