The 28-year-old, who is also a jockey with a career of three winning rides, said, "I had hoped to go hard out in the second half but I didn't know what to expect - I'll probably go slower in the first half next time."
The half marathon, won by Stephen Lett, of Takapuna, drew more than 7000 competitors.
St John Ambulance officers reported a busy day treating cases of dehydration and extreme exhaustion, as well as the usual complaints of blisters and rolled ankles.
Mayor Len Brown and wife Shan Inglis took part in the Heart Foundation 5km run and walk.
Mr Brown had a heart attack three years ago and was happy to help raise money for the foundation and an event which is a tourism boost for the city.
Race director Richard Lindroos said the event drew 600 international competitors. "But more than 1500 international visitors would have been there because each competitor brings someone with them."
About 5500 competitors came from outside Auckland, adding to the city's drawcard as a tourist destination.
Despite the demand, the number of marathon places is capped because of the need to close parts of the roading network.
Mr Lindroos said the adidas-sponsored event had 500 more long-distance runners than last year's runs. Places for the full and half marathons sold out in five weeks.
"We are keen to increase the size of the fields but growth must be managed step by step and have full operational support from Auckland Council.
"We have the Rugby World Cup, so why can't we be in a global eventsmarket?
"If you want to live in a big city, a First World city and a known tourist destination, you would put up with roads being closed for a few hours on a Sunday morning."
The foundation's team of 350 Heart Racers, which ran the longer events, raised nearly $100,000 in sponsorship.
One of its runners, Zoe Green, of Auckland, said she decided to enter to support a friend, Chris Britten, who had a pacemaker installed at the age of 22.
"He did the full marathon last year, so I thought if he could do that, I could drag my way through."
One of those who finished the half marathon smiling was Aucklander Raeone Dellaca.
The veteran of many tough events said she had decided to enjoy thisone.
"For me, this event has loads of atmosphere. It's the onlookers. The people beating the drums as you are going on to the harbour bridge and starting to get tired. It's a great experience."