"It was the first one we wrote for the album," Tonnon said.
"It started as a ballad, and I'm not the world's greatest pianist, so Jonathan wrote me the great 'left hand' part that you hear. You need really stretchy fingers to play it.
"He also helped come up with the descending chords just at the end of the main body of the song."
While he had the music and hook "early on", it took two years to complete the lyrics, Tonnon said.
"We finished it, but it felt like it needed something more for the live set.
"I've started playing with drum machines, with songs like Two Free Hands, and it felt a little bit underwhelming just playing a three and a half minute piano ballad.
"That's when I came up with the idea of just pushing a button and having this big outro, and having that guitar solo came in.
"That outro really came out of live experimentation."
The song's chorus was "one of those beautiful accidents", Tonnon said.
"It's a bit unusual for me, it's more soul or jazzy than I'm used to.
"You're hitting the piano and you accidentally hit the wrong note on the left and somehow it sounds right."
Tonnon said songwriting wasn't something that had got easier for him over the years.
"It's something I love and it's something I perpetually chase, but it's always difficult.
"I spend longer and longer trying to make the perfect song.
"What's great about having Jonathan is that he knows me really well - we've been working together for a decade.
"I'm a big believer in pushing through and working with the same team for a long time, rather than constantly changing it up. There's a real value in that."
• Anthonie Tonnon will be playing with a full band at the Royal Whanganui Opera House on Saturday, October 2.
