"I was told if I didn't have the heart valve fitted I would only have two years to live so it was an important procedure.
"I've then had to wait a while longer, although age has started to catch up with me. I ran six hours 12 minutes three years ago in my last appearance and this time around I'd be pleased to do eight hours 12 minutes."
Garth was introduced to running in his mid-50s and made his marathon debut at the 1990 Rotorua Marathon.
He has since gone on to be become a Survivors' Club member - in which a runner needs to complete 15 Rotorua Marathons - and has also completed ten NZ Ironman triathlons.
He described discovering his passion for endurance sport at a relatively advanced age as "a novelty" and recalls the buzz of reading for the first time in the NZ Herald that he had placed top three in his age-group for a triathlon.
"I spent my whole life with my name beaming down in big capital letters in those Barfoot and Thompson ads but to see your name in small print, well, money can't buy that."
His health and age have slowed Garth in more recent times.
He completed the Auckland Waterfront Half Marathon this month in 3:48, so he is realistic about what he can achieve in Rotorua this year.
"Using my coach's rule of thumb of 'your marathon time is twice your half marathon time plus 25 per cent' – this makes 8:32 as my predicted marathon time.
"Last year's slowest time in Rotorua was 8:29, so I still have some work to do and there are hills in Rotorua, real hills.
"But the race is still special to me because it is where I ran my first marathon. It will still be quite a thing if I manage to complete the race, and I will probably be the oldest Aucklander ever to finish the Rotorua Marathon."
Multiple roads will be closed for the Rotorua Marathon on Saturday, May 8. For details go to the Rotorua Lakes Council website.
The details
- What: Rotorua Marathon, with full marathon, half marathon, 10km and 5.5km
- When: Saturday, May 8, 6.30am to 4pm
- Where: Energy Events Centre
- Race and entry information at www.rotoruamarathon.co.nz