It is 63 days until polling day on October 12.
Mr Garvan said the decision was timed so that he could travel before winter in the northern hemisphere.
And he noted his departure would not cause a by-election prior to the coming election.
He had been considering the personal decision - about taking on another three years at the council versus having more time for himself and to spend with his wife Debbie - for some time.
"I've been seriously thinking of not standing for over six or nine months," Mr Garvan said.
At the time he entered local politics, in 2007, there was a shift in politics in the Waitaki as the public recoiled against spending on the restoration of the Oamaru Opera House.
Mr Garvan had just sold a Wear St sharebroking business he co-owned and mulled the decision over.
"I looked at standing and I thought the opposition was too strong and decided not to stand - and then I got a phone call from a friend ... who said would I stand for the licensing trust? They didn't have the nominations, they were short - and I thought `OK if I'm in for one, I'm in for both'."
He said he expected to get on the licensing trust, but he lost out.
But he was one of two newly elected councillors, along with Cr Jim Hopkins, to form the new council under Alex Familton's mayoralty.
There was "a lot to learn" for the former University of Otago political science and law student.
"You learn how to approach things and how to be effective. A lot of things are to do with personality and if the right person puts something forward, who's got mana, it bolts through. And the same speech from someone who is not popular wouldn't go through, in some cases," Mr Garvan said.
"...You learn you've got to get a feel for where your other councillors are at."
He viewed the council as an "enabler" for those with the confidence to invest in the district and not "a policeman".
He served nine years on the board of the Oamaru Whitestone Civic Trust.
He spent three years as the chairman of the council's harbour area committee.
Over the past year, he ran a series of ads recently in the Oamaru Mail and the Otago Daily Times expressing his views on harbour issues in an "unfiltered" form.
And he would remain interested in heritage, the district plan and the harbour.
"I'm not for unrestrained commercial development in the harbour area," he said. "It's a small space. It needs space. It needs a sense of tranquillity. It needs view shafts," Mr Garvan said.
Serving as a councillor was a "positive" experience, as was watching North Otago grow. And he said he hoped the district's employers were flexible and pushed the district's lifestyle as a way to attract young families.
