"I thought before I start to fall to bits, is there anything else I'd like to do while I've got these high fitness levels? Coast to Coast was the obvious thing."
Speights Coast to Coast is divided into three races - the One-Day or Longest Day is for individuals only while the Two-Day event is for individuals and two-person teams. In the team's section the runner and the kayaker both do cycling stages.
McGuire, a district court judge, has had to juggle his commitments to work and training. On average he trains anywhere between 15 and 25 hours a week.
It has meant he has had to get up and train in the early hours of the morning before work and late at night after work.
But the long hours have not dampened his determination to do the best he possible can come February 11 when he lines up on Kumara Beach near Greymouth.
"Well, I love to try and do things well and I'd like to try and do it under 15 hours and I'd be very happy with that because just looking at the times of us old guys, that would be quite competitive."
McGuire is not the only Rotorua local taking part in next year's event. Owen Hall, who competed in the two-day individual last year, and Rebecca Law will compete in the longest day, while Mark Beesley and Cuncan Bourne will compete in the two-day individual. In the team section Chris Macklin and Fletcher Pilditch are competing as the Gordon Pilditch Panthers.
The two-day team and individual races start on February 10 with the Longest Day the next day.
The Speight's Coast to Coast is the brainchild of Robin Judkins. In 1982, with 11 mates he pioneered the same 243km course used today. The first official race was held less than a year later on February 26 and 27, 1983. Judkins had planned for a field of 35 but was surprised when 79 entries were received.
The look and feel of the race was considerably more relaxed than today. One of the bikes even had a baby seat and there was a kayak made of canvas.
In 1984 the field grew to 139 competitors and a year later entries leapt to 320. The Speight's Coast to Coast had arrived.
More than 450 competitors have registered for next year's event which celebrates its 30th anniversary.