In the 2005 election Guy, who did a lot of dogged groundwork, missed by 382 votes, making it "the most marginal seat in the whole country" before winning it in 2008 by 1354 votes.
After impressing in a parliamentary rugby team, Murray McCully told the party Guy had enough mongrel to be a whip.
Guy soon became junior whip and then senior whip, all the while soaking up how Parliament worked.
"It was interesting for me the cut and thrust of this place.
"It's intimidating. It's a bear pit, that's its nickname, and it probably will never change. But for me, that was my opportunity, ultimately, to pick up a ministerial warrant."
He became Veterans' Affairs Minister and did a battlefield tour of Gallipoli as well as speech in front of 6000 people, both of which he found emotional.
On the electorate front he championed the Mackays to Peka Peka Expressway which upset a number of people.
"I had to bear the brunt of that in my electorate office with people coming in in tears.
"But, ultimately, it was the right decision and I backed it all the way."
When got his "dream job" as Minister for Primary Industries there was a baptism of fire.
Meat was locked up on China wharves, then there was a Fonterra botulism false alarm, before "an idiot" sent a letter saying they wanted to contaminate infant formula with 1080 poison.
"I was worried about an infant dying."
One of his "proudest moments" was how his department stepped up and worked with the dairy industry.
"We set up a whole testing regime from cow to can, and the day it became public, there were no border ramifications."
Another high profile issue was when Guy released a discussion document about reducing the snapper bag limit [from 9 to 3] in the Hauraki Coromandel area.
"All of those fishers wanted Guy on the hook.
"Ultimately I made the right decision in the end for sustainability purposes, reducing the bag limit to seven."
As he packed some cardboard boxes in his office, he found a newspaper article about him from a number of years ago.
"There's a quote in there I want to read out to you: 'It's easy to sit on the sidelines and criticise. It's a lot more difficult to stand up and be counted'.
"I won't forget the last 15 years.
"I'm sure Parliament won't miss my booming voice.
"Kia kaha my friends and foes.
"Haere ra."