He told them officially late last month and broke it to the rest of the rugby union crew on Thursday.
"I've received some really lovely tributes from the board - it's been quite emotional."
The decision was spurred by having put in a devoted dozen-year stint in the top role, and feeling he had got the union to a good place which meant it was a good time to move on and "let someone else sit in the chair".
His partner has been living and working in Auckland for the past few years which had meant "a lot of commuting" and all but one family member had moved away.
"For me, it's the right time," Bishop said, adding that his options for what lay ahead were still pretty open at this stage.
"I'm working on a few things - got a few options and yes, sport could possibly be involved."
Bishop said his reasons for leaving involved no other issues, but said there would be people who would decide to say otherwise.
"And you'll always get that."
The walk-out of two of directors in March and the fall-out from that had not been an issue, and Bishop said there had been nothing wrong with the business workings of the union at that time "and as of now still nothing wrong".
His summation of the director walk-out was to the point.
"Their behaviour was disgraceful and they should be ashamed," he said.
"In March it got toxic - there was a lot of talk going round in the street at the time and that was a real shame, and the frustrating thing is that there was no need for it and it cast aspersions on the union."
Bishop said the union currently had a well balanced board with a range of business, club and community experience, and the union was in good health.
"We are heading for a surplus and that will be 12 in a row."
He said he would miss the rugby union "family" and miss the passion and devotion of everyone involved.
"We all enjoy each others' company and we operate so well."
It had been that way since day one when he arrived on August 3, 2005, and where his initial set-up was "a laptop on my knees."
Before taking on the role he had worked with the Wellington Cricket Association then as chief executive of the Marlborough Rugby Union and as provincial union relationship manager at the NZRU.
He took on the role for two reasons - he was born in the Bay and he had a passion for rugby, as well as a challenge.
Bishop said working alongside people like chairmen Richard Hunt and Brendan Mahony and board members like Steve Lunn, Peter Fleming, Grant Gilbert and Colin Francis and the whole union crew had been a privilege.
"There has always been so much deep knowledge and passion for the game."
He had also been overwhelmed with the devotion of sponsors through the years, and paid tribute to the "outstanding tenure" of their principal sponsor Craig Hickson.
"We have some fantastically loyal sponsors - in some cases some have been with us for 20 or 30 years."
There had also always been a real passion from the army of keen volunteers who worked alongside the officials during the staging of major events.
"The public would have no idea what has to go into staging these big games," Mr Bishop said, adding his role had been far from a 40-hour week.
At that suggestion he laughed.
"Oh no, it's more than a job ...i t is a vocation and a lot of time has to go into it and there can be plenty of stress with that."
But long hours and constant business and operational challenges had been easily balanced out by what the Magpies had delivered during the time he has been CEO.
They picked up the Ranfurly Shield twice, made the national semis three seasons on the trot, took the championship title and have produced well over a 100 Super Rugby players and several All Blacks.
"And we have more kids and women playing the game today - everyone is working together at all levels to grow the game."
Hawke's Bay, he said, had built a nationally recognised and respected rugby image and he was proud of what had been achieved.
"It has been an amazing ride and there are many aspects of the job that I will miss," he said.
"And there are aspects of the job I feel I've done the best I can - so it is time to hand it over to someone else."
Bishop said he had been fortunate to work with some "amazing" people as well as meet some high profile officials and players from all over the world.
"And being a Hawke's Bay lad, and with my parents still living here I'll be back all right - and there's only one team I'll always support of course".
It was something his parents used to tell him when he was a lad that he holds close in terms of taking something on.
"Try as hard as you can try, and do the best you can do," he said.
"It hurts to go but hey, it's time to go and Hawke's Bay will always be dear to my heart."
Board chairman Brendan Mahony said its directors were releasing Bishop "with the greatest regret and wish him well in whatever new ventures his talents and abilities may now lead him".
"Mike has led Hawke's Bay rugby through many testing periods of rugby development in New Zealand. His dedication and ability to remain flexible in his approach has seen him held in the highest esteem throughout New Zealand rugby circles," Mahony said.
HBRFU's success over the past 12 years was a testament to his tenacity and foresight. His ability to develop and lead a loyal and committed staff has played a large part in his success.
"Mike's many positive personal qualities have enabled him to interact positively with chairmen, directors, players, coaches, sponsors throughout the country and the wider Hawke's Bay rugby community over the 12 years of his outstanding service to his province.
Bishop had served Bay rugby loyally and the passionate 'Magpie Man' "is due our gratitude".
Mahony said the board would appoint a new CEO in the new year.