"The mountain looms before you in the distance and you know you must tackle it step by step.
"It seems impossible at the start, but working at it, improving fitness and appreciating the improvements allows you to eventually complete that challenge and, when you do, it's the most amazing feeling ever."
Mr O'Malley, the Queenstown Lakes District Council's infrastructure services strategic project manager, will leave Queenstown on October 26 bound for Nepal, where he will undergo final preparations for the 42km run, listed in the Guinness Book of Records as the highest marathon in the world.
The start line is at Gorak Shep - at an altitude of 5184m - close to Everest Base Camp in Nepal, finishing 42km later in the Sherpa town of Namche Bazaar at an altitude of 3446m.
It will be the 14th time the event, organised by Bufo Ventures Ltd, has been run. It raises money to support health and educational projects in rural Nepal and 50% of the money raised by runners goes to a nominated charity at home.
It will be Mr O'Malley's first marathon.
"Start with a bang," he said.
"I haven't done a marathon distance but I have done a 60km - the Kepler." Mr O'Malley's charity is Jigsaw Central Lakes - chosen following a series of articles focusing on various forms of abuse published in the Queenstown Times in conjunction with Jigsaw and the It's Not OK campaign earlier this year.
Jigsaw is a national network of more than 40 independent, community-based, social service organisations working to stop child abuse, neglect and family violence.
"It's almost a taboo topic that people don't want to hear about. What I would love to do for Jigsaw Central Lakes is get the awareness out there. Hopefully, that will be really good for them and the people they help."
Mr O'Malley is no stranger to fundraising, having helped organisations which deal with depression in his home country, Ireland, following a personal tragedy. His brother, Michael, committed suicide 18 years ago and Mr O'Malley struggled to cope.
He described his brother's death as "creating a vacuum" in his life which was subsequently filled with alcohol and depression.
With support, he was eventually able to deal with the issues around Michael's death.
"I believe it's important to give something back and I greatly admire what Jigsaw Central Lakes do in helping deal with issues that relate to mental health and wellbeing."
After hearing about the Everest Marathon, which caps entries at 70, two years ago, Mr O'Malley registered 18 months ago and entered in November.
Arrowtown resident Ken Hardman has also entered, choosing Cure Kids as his New Zealand charity.
Mr O'Malley said he had been training on Queenstown Hill, Ben Lomond and the Remarkables access road - "uphill-downhill tracks which are reasonably rough as well".
After a few days in Kathmandu, Mr O'Malley will begin a 15-day trek to acclimatise, climbing Gokyo Ri (5483m) and Kala Pattar (5623m) before the marathon on December 2.
To make a donation to Mr O'Malley and Jigsaw Central Lakes, visit http://uk.virginmoneygiving.com/JigsawCentralLakes
