He delivered about 1000 babies during that time and said that was one of his career highlights – the satisfaction of bringing happiness to so many families, many of whom he continues to look after.
In many cases, he has cared for four generations of the same family.
Gemming said his overall career highlight had been the continuity of care he has been able to provide.
"I'm very grateful to Tauranga to have had this opportunity to basically be helpful, and I've found it very rewarding," he said.
Gemming was born in Tauranga and went to Te Puke High School.
Growing up on a farm and looking after animals, combined with an interest in science at school (in particular biology), led him to medical school at the University of Auckland.
After six years of study, he began what would eventually be a 44-year career as a doctor.
Gemming was instrumental in developing the Western Bay of Plenty Public Health Organisation (PHO) in 2003 and was its inaugural chairman until 2016.
Before that, from the early 1990s, he was the secretary/chairman of the Prime Health Network, an organisation that preceded PHOs and co-ordinated general practice.
He also spent time on the executive of General Practice New Zealand.
So, was he happy with his choice of occupation, all these years later?
"Very much so," Gemming said. "It's been a wonderful career."
He is not, however, hanging up his stethoscope for good.
Gemming will continue his involvement with the International Hockey Federation, serving as tournament doctor at events around the world.
His next appointment is in Kuala Lumpur at the end of April, at the men's FIH Hockey Series Finals.
Gemming is also involved with New Zealand Hockey, in particular with masters' teams.
He still plans on doing a bit of locum work as well, and Fifth Avenue Family Practice might always call him back in if ever they find themselves short during a busy period.
Gemming is also a medical referee, certifying various legal documents to make sure they're legitimate.
His retirement from daily practice does mean there will be more time for hobbies, however, of which he has a few – swimming, gym work, cycling, gardening, windsurfing, surfing and fishing.
There will also be more travel and adventures around the world and, of course, more time with family.
His wife Gill is the Oceania Hockey Federation's development manager, which takes her all around the Pacific.
Gemming plans to join her on those trips more often now.
There are also their three sons and their families to spend more time with, including seven grandchildren aged between 1 and 11.
