Cormack - who has lost half her body weight during the past 18 months - achieved the "massive milestone" on Saturday by completing the 10km fun run at the popular marathon.
"If two years ago you had told me that I was able to run in the 10km race I would not have believed you," the Napier woman said.
"This is a massive milestone for me and I couldn't be more happy with how it went."
Organisers of the event have estimated the economic benefit for the region to be over $7 million, with thousands of participants coming from out of town to take part.
Remarkably, a new record was set in both the men's and women's marathon, albeit on a slightly adjusted course.
Michael Voss (Rotorua) won in a time of 2h 24m 2s and Ingrid Cree (Wellington) in a time of 2h 49m 34s.
Hawke's Bay Marathon winner Michael Voss. Photo / Ian Cooper
Hawke's Bay Marathon women's winner Ingrid Cree in action. Photo / Ian Cooper
Another astonishing story during the event was that of Havelock North's Di Snee.
Like Cormack, Snee also completed the 10km fun run and walk, alongside a team of support walkers who were wearing hi-vis pink vests.
Snee has been diagnosed with terminal cancer, but she decided to take part in the event again this year which she has entered many times previously.
"There's so much support it's unbelievable," she said.
"One of my girlfriends has come over from Australia and lots from New Zealand supporting me in this one, so it's very, very special.
"I've always done the half marathon and I knew this year I would not be able to do it so I said, 'come on, join me' [in the 10km] and they all have, very willingly."
A variety of distances were available at the event including the full marathon (42km), half marathon (21km), and 10km fun run and walk.
