"It's a loading injury. Too much load and the bone can't handle it and gives way," Harris told the Herald on Sunday. "I've been managing that since the end of 2016. I originally felt it in the test match in Perth against Australia."
That game, David Kidwell's first match in charge, was played on October 12, 2016.
Harris got through the subsequent tour of England, where the Kiwis reached the Four Nations final, before reporting for duty at the Melbourne Storm in early 2017.
"I thought it was an ankle [problem]," said Harris. "During pre-season, I got a scan and found out it was a stress fracture. Had to manage it through that 2017 season."
Harris missed the first nine matches, allowing the condition to "settle down", but returned for the second half of that campaign, a key part of the Storm's emphatic premiership triumph.
After making the switch to Mt Smart, Harris delivered on his marquee status in 2018, especially early on. He was imperious in the first 10 matches, as the Warriors won an unprecedented eight games.
But his foot condition flared up again last year, as well as knee problems. He was ever-present throughout the first half of 2019, albeit on a reduced training load.
"It had been bothering me for a number of weeks leading up to [the Titans] game," said Harris.
"[Then] some time in the first half, it happened, I didn't really know what it was. I started the second half, couldn't run, couldn't put weight on it. I got a scan and saw that the bone had broken.
"It might have been a certain movement, or something happened and it just couldn't handle it.
"I'd managed it the last few years but it got to the point where it just got too much and ended up cracking properly."
After that, Harris didn't play another minute last season, and he was missed, as the Warriors won only four of their last 11 matches to slump to 13th.
The recovery process has been slow but fruitful, and the operation (inserting two screws) was a success.
"I've been able to do most of the trainings and just keen to get back out there," said Harris.
"It's something I have to be aware of, in case it pops back up again. But it's feeling really good.
"It's the first pre-season where I have been really excited to get out there and do everything because it has been so long since I have been with the team and playing."
Harris is also thriving on the approach of new Warriors head trainer Craig Twentyman (who has previously worked with the Wallabies and Australian rugby sevens teams), after the departure of Alex Corvo late last year.
"They are pretty different in how they operate, although both have their benefits," said Harris.
"[With] two years under Corvo, we've come into this year with a really strong base in our fitness levels.
"Now hopefully Craig can help us go to the next level."
Ahead of the club's NRL season opener in Newcastle on March 14, the Warriors have trials against the Storm (February 22, Palmerston North) and Tigers (March 1, Rotorua).
