"When you've had to struggle to get to a world championship, having to get yourself on to trains all over Europe, doing it on your own, having to stay in dodgy little backpackers - when you get to the start line, you're so fiercely determined."
Endurance running is a lonely sport that involves constant sacrifice. Moon's breakthrough in Italy was liberating for her, because it meant she had something tangible to show for the huge amount of effort she had expended.
"I always remember that moment of crossing the line," she says. "I thought, 'I've finally done it. I can retire, or if I get injured, I've [still] done it'."
Moon had tried all aspects of athletics before she found her niche in mountain running.
"I was always naturally suited to the things that were broken rhythm, that required leg strength and a bit of mental toughness," she says.
That toughness endured beyond her mountain-running days. In 2010, Moon won a stair race to the top of the Empire State building in New York as part of the Vertical World Circuit, which involves races up the world's tallest buildings.
"It was a natural progression," says Moon. "I had done everything I could possibly do in the world of athletics and I needed a new challenge in life."
Melissa Moon was a two-time world mountain-running champion. Photo / NZPA
Moon doesn't compete any more but, true to form, has found a way to keep herself pounding the capital's footpaths for a while yet. In July, she was asked to support a blind woman named Maria who wanted to start running.
"I've had the privilege of running freely, and this person is relying on someone just to get out," says Moon. "So I said, 'absolutely'.
"It went from one day a week to two days to three days, to setting a goal of competing in the Auckland Half-Marathon, which has just gone."
The pair are now thinking of running the London Marathon together next year.
Moon believes life is made up of small moments and, because of that, she doesn't like to think what her future will hold too far in advance.
"I just see in the next months being on that start line in London and leading Maria to achieve a wonderful sense of satisfaction. I know what running has given to me. Wouldn't it be wonderful to let her share the same experience?"