Imms said he first joined up to have a good time with a bunch of mates with similar interests.
"If you'd told me when I'd joined I'd still be here in 50 years I'd say you had rocks in your head … but it gets in your blood," he said.
"It's not only what you give to the community. It gives you self esteem, confidence and purpose in life. I'd still think twice about saying I enjoy it but it's like anything, you get out as much as you put in."
Imms said a lot had changed since the early days when firefighters spent more time fundraising for equipment than putting out fires. These days their equipment and fire engines were provided, but the volunteers were expected to spend a lot more time training.
Callouts that stick in his mind include the 1980 floods that devastated Kerikeri and a horror crash at the top of Bulls Gorge that left half a dozen dead, including children.
The former deputy fire chief said he had no plans to quit – "not tomorrow anyway" – but he would stand back a little more and make way for younger members to step up.
More than 200 people, including firefighters, family members and community leaders, gathered at the Turner Centre in Kerikeri on Saturday to honour Imms' 50-year volunteer contribution.
Fire and Emergency NZ (FENZ) Muriwhenua area commander Wipari Henwood described Imms as a poutokomanawa, the central post of a wharenui or meeting house, which is key to the stability of the entire building. He also paid tribute to Imms' wife, Vivienne, and the sacrifice made by volunteers' families.
"Greg and Vivienne, you are the poutokomanawa of this brigade, and the community," he said.
MC Dave Clark, a former Kerikeri firefighter, said every brigade needed someone like Greg Imms. The amount of time he had given over the past 50 years was "incalculable".
Imms was awarded his 50-Year Medal by former United Fire Brigades Association president, and Kaitaia fire chief, Colin "Toss" Kitchen.
Kitchen said Imms was just the second firefighter in Kerikeri to receive the honour, after the late Ralph Rogers, and the 15th in Northland.
As Sir Colin Meads was to rugby and Sir Edmund Hillary to mountaineering, Imms was "in the same vein in his contribution to Fire and Emergency NZ".
Others who lined up to pay tribute to Imms' volunteer effort included FENZ deputy chief executive Kerry Gregory, Far North Mayor John Carter, Northland MP Matt King and Northland police Inspector Chris McLellan.
Also honoured on Saturday were deputy fire chief Kevin Graham, station officer Andy Hamberger and qualified firefighter Ngaia Cruden, all of whom were awarded 14-year Long Service and Good Conduct medals.