Coaching for the former All Black is an all our nothing proposition. No matter the job, he has to be fully immersed - head, heart and soul.
And that's why he's back with the All Blacks for what will be a 13th test season. They are the team to which he simply can't say no.
"I had a genuine look at Harlequins and Trish [his wife] was quite keen on London, too," said Smith. "We had enjoyed our time there before but because I knew that I wanted to be boots and all in any coaching job I took, it became pretty obvious what I was going to do."
What he was going to do was say yes to the offer All Black coach Steve Hansen had made him early in the year.
Smith signed a one-year contract in late 2014 to be the All Blacks defensive co-ordinator in World Cup year. When he agreed, he was adamant he wanted to take a break from the game after the tournament.
He'd been involved for 29 years without a break - holding coaching jobs with Canterbury, Crusaders, Northampton, Chiefs and the All Blacks.
He deliberately had no contract to go to and nor had he given his next career move any thought. In the aftermath of the World Cup he and his wife travelled New Zealand in their motor home and reconnected with the South Island.
It was a good time, everything he wanted and needed so when Hansen made his offer, Smith was ready to listen.
"Steve had talked to me a bit before the end of the World Cup," says Smith. "He had joked that I would be back and I was adamant I was done. I really felt I had done my dash.
"When I came back in 2015 I was concerned about whether I would be able to make a difference. I had worked for a long time with Richie [McCaw], Daniel [Carter], Ma'a [Nonu, Conrad [Smith], Woody [Tony Woodcock] and Kevy [Keven Mealamu] and I was concerned whether I had maybe worked with them for too long."
What he found was that he was able to have an influence and make a contribution and he also came to see just how much the All Blacks were going to miss the so-called Golden Generation in 2016.
That was the point Hansen was able to make - that the All Blacks needed Smith's experience, attention to detail and deep knowledge of the game to help rebuild the team.
There was no point in pretending, the challenge of being successful without the likes of McCaw and Carter will be extreme.
That appealed to Smith - the opportunity to defy the odds. And so too did the expanded role.
He'll be responsible for defence, counter attack and some skills in 2016. He'll also have some input into selection - not formally, but he'll be able to feed data into the mix and have his say.
"I see the challenge as not being too dissimilar to the one Harty [former All Black coach John Hart] faced in 1998," says Smith. "They lost a lot of experience back then and that's the same with this team. But I got into coaching because I am still competitive and I love the contest so this is going to be a great challenge."
- Gregor Paul