"I believe that what motivated us was Phil Hughes. We knew we had to play and we would do that as best we could, to honour Phil and the game itself.
"The outcome of the 'uncaring', no consequence play was a revelation to me.
Watch: McCullum on respecting the opposition:
Watch:McCullum on retirement:
"I suspect it was something I had been trying to achieve on a personal level for years; but I had been unable to do so, except for fleeting moments. Here there was a release of many of the external factors that can creep in and influence a player.
"There was an instinctiveness that took over - no fear of failure, just playing and being 'in the moment'."
McCullum also openly discussed the change of approach under his leadership, describing his desire for the side to "personify the traits that we identified in New Zealanders - to be humble and hard-working."
McCullum added: "We wanted to be respected by our long-suffering fans in New Zealand.
"We wanted to be respected by our opposition; and before we could demand this we had to learn to respect them."