The back rower has been unable to train with the team due to a lingering knee injury, before producing lung-busting 80-minute efforts each weekend.
"I can't get through a full week of training," Harris revealed to the Weekend Herald. "The last three weeks, it's just been the captain's run."
The 27-year-old tore the meniscus in both his knees last year, and had post-season micro surgery to remove some damaged cartilage.
He re-injured the right knee playing the Melbourne Storm on Anzac Day and has been hampered since. It won't require surgery but has been complicated to manage.
"I was able to train with the team this week [on Wednesday night], which has been really good," said Harris. "It's been the most training I have done in the last month, so I'm pretty happy about that."
It means he is more prepared for an intense battle tonight against the Brisbane Broncos at Mt Smart Stadium, after coming in cold for the games against the Knights, Dragons and Panthers.
"It wasn't ideal," said Harris. "Conditioning-wise, it makes it a bit harder. But you get through it."
Harris has been ever-present this year, one of only six Warriors players to feature in all 10 rounds. He's averaging 11 runs a game and 100 metres, and has also contributed two tries, three try assists and 12 tackle busts. Harris also has 27 tackles per game and 16 one-on-one stops across the season.
Harris sees two catalysts in the club's recent turnaround.
"We've got a bit more belief," he said. "We haven't all of a sudden got better or anything. We are still the same team. We have just got more confident and as a team haven't had as many of those slow patches, where other teams were really hurting us.
"[The other thing is] our defence. That's where we get a lot of confidence from and that's been the really pleasing aspect of the last two weeks.
"That's what the big teams build their games on and that comes from training intensity. That's where it pays off. Last week and the week before, we made huge inroads in terms of getting that belief."
Harris has been impressed with the contribution of Kodi Nikorima since he arrived at the club.
"He's brought a lot of confidence," said Harris. "He's had a bit of experience in big games and international games. He's a confidence player. It has helped to rub off on players."
Assistant coach Todd Payten confirmed Ken Maumalo and Lachlan Burr would take their places in the 17, after being rested from some training sessions during the week, ahead of what is expected to be a bruising clash with the Broncos.
"They are a young, athletic, dynamic team," said Payten. "They have a lot of guys who can break tackles and offload the ball and we need to be really sharp with our first contact defensively."