Well you start as the governor of the Bank of Canada for 5 years, then the governor of the Bank of England for another 7. After that you spend about 5 years in private finance. In parallel you spend that time acting as an economic advisor to multiple governments. Then the day comes where a major party needs a new leader, all the existing senior leadership either doesnt want it or is some manner of "problematic" and anyways, its not like they're going to win. Then whaddaya know, turns out Canadians like the idea of someone whose spent their whole life in macroeconomics at a time when global economics are all kinds of fucked up.
So it wasn't overnight, but it was a case of just the right person at just the right time.
