A digital business manager raising money for the New Zealand Mental Health Foundation says it is a cause that needs to be supported.
Joshua Herbst, who himself was diagnosed with ADHD in his 30s, is fundraising while training for the Taupō Ironman marathon.
That consists of 3.8km swim, a 180km bike ride, ending on a 42.2km run.
Herbst is training every day to get ready before the Iron Man, which will be held in March.
"I've ramped it up in the last week or so, now it's getting quite intense," he said.
Herbst explained he trains twice a day, swimming, running and cycling, with just one days break in a week.
He said he wanted to start the conversation around the importance of diagnoses.
"Since I got diagnosed, my life changed drastically, it got better in every imaginable way," he said.
He said his personal life and career have all benefited from his ADHD diagnoses, and friends who have had the same echo his sentiment.
Herbst said when he first started, he had no idea what he was in for.
Since his training began in August of last year, Herbst has run, swum, and biked 1280km.
"The mental part of it is probably the hardest, waking up every day and doing it again when you're exhausted from the day before."
The intense training sessions help Herbst stay focussed on completing his goal, something his ADHD typically makes difficult to do.
The Taupō Ironman takes place on 4 March, and is the world's second longest-running Ironman marathon.