"I fancied myself as a middle-distance runner," Heine said. "I entered the marathon as part of a training run for my middle-distance stuff."
About two-thirds of the way through he realised he had a chance of winning.
"I thought I could pick up a few of the guys in front. I don't know if it was me coming through or them dropping off, but I won."
Heine won the first marathon in 2hr 35min 3sec.
He said he was pleased at the time but the win gained significance as the years went by.
"People keep reminding me of it - just the fact that it was the first one. It is quite good to look back at, that is for sure."
Heine, who is now in his 70s and based in Hamilton, said he had planned to do the marathon again this year for the 50th anniversary. However, a knee injury has ruled him out.
Heine said he was still looking forward to arriving in Rotorua this weekend to meet some of his old friends, such as Dennis Kenny, and to send the marathon runners on their way.
Heine said back in 1965 the course was run anti-clockwise around Lake Rotorua but it had not changed much in 50 years.
"It was always attractive. Having one lap of the lake equate to almost a full marathon is quite a coincidence."
Heine, who grew up in Auckland, spent about three years living in Rotorua as a young engineer before moving away.
"[Rotorua] was just an enjoyable place to run and the club had a great social set-up."
Among his running buddies, Heine used to rub shoulders with fellow Rotorua Marathon winner Jack Foster, well known as one of the best runners to come out of Rotorua.