McCullum spoke at length about his record-breaking 302 runs against India in the second Test, preventing the visitors from drawing level in the series. The Black Caps won the first Test in Auckland by 40 runs, and with it the series 1-0.
"My innings was what was required at that stage (94/5). We were obviously scrapping to save the Test and therefore win the series, and we managed to get some partnerships under pressure. And then kept batting and batting and batting. So it was pretty satisfying to get us out of trouble and claim the series win," said McCullum after the match ended.
McCullum's innings was the highest score for a New Zealand batsman in a Test innings, overtaking Martin Crowe's 299 against Sri Lanka, also scored at the same ground in 1991. He became the 24th batsman in the history of Test cricket to score a triple-hundred and join this exclusive club.
"I wasn't feeling nervous until I saw the size of the crowd. That's probably when I understood the magnitude of the task at hand and the immense joy it gives fans of this cricket team to see guys succeed and see records broken," he said.
"It was a moment, when the 300 came up and the applause was ongoing for quite a while, it is really when it hit home to me that it was quite a significant achievement for a New Zealander and I'll certainly remember them for the rest of my life," he added.
Despite the achievement, McCullum was humble at his success and said that he was not as talented as the legends of New Zealand cricket.
"Without being disrespectful I probably didn't know the magnitude of it until the last 24 hours. I grew up and watched the New Zealand cricket team for years," he said.
"I watched Martin Crowe score his 299 and thought it would have been an amazing feat if he scored 300 but probably didn't quite understand how much it meant to the whole country who support this team. I also spoke to Stephen Fleming last night. I feel a little bit embarrassed because I'm nowhere near the calibre of players they were."
McCullum became the second-ever New Zealand batsman to cross the 200-run mark in a Test innings thrice, after Fleming.
The 32-year-old shared a record 352-run partnership for the sixth wicket with BJ Watling and then James Neesham smacked a maiden Test hundred on debut to further rub salt on the Indian wounds.
"Thankfully I had partners at the other end who also played brilliant innings. I thought BJ and Neesh, their innings were outstanding. BJ's in particular because he came in when we were five down for 90-odd and he obviously came off a duck in the first innings as well. To play an innings like that is testament to how strong a character he is," he said.
"Then Neesh in his first Test match, with the game still reasonably poised to come out and play his natural game, which is aggressive, takes a lot of courage, so I was pretty lucky to have those guys there. Then I had to fight the emotion when I hit the ball a bit harder than I was trying to hit and make sure of the team goal first and foremost."
New Zealand didn't declare until late into the first session on day five, leaving 435 runs for India to get in two sessions, an impossible task and one that sealed their fate in this series.
"We were 1-0 up in the series and, two and a half days ago we were staring down the barrel of an early finish on day three. We didn't want to pass up all that good work we had done to try and give India a sniff back into the series.
"I always try and win but at some point you've got to acknowledge the game was out of your reach and then you fought your way back into it. Hence we made sure we got a score where we knew we were going to lose and then we could be as aggressive as we wanted, and hopefully if we got some early wickets then some pressure might set in. But they're class players and they stood up," said McCullum.
McCullum would be thankful to Virat Kohli too as he celebrates the achievement, given that the triple century couldn't have happened if the Indian hadn't dropped him when he was on 9 runs.
"I'm not sure what sort of wine Kohli drinks but he probably got his bit of karma back this afternoon (scoring a hundred after given not out off a visible edge). I very much appreciated him putting that one down but thankfully I didn't offer too many chances after that," said the star batsman.
"I'm going to have a quiet beer with my team-mates. Just catch up with the boys and pledge up in the changing room and just reflect on a season that's been pretty important for us and the game in New Zealand," McCullum signed off.