It's torture. It's a shit fight.
It's a road to recovery so long a voice in the back of your head is waiting for a moment to pipe up and tell you to give in, because "this is too much", because you can't handle having your dream taken away.
The comeback trail from an anterior cruciate ligament tear can feel like a lonely place. But there along the way is a face less familiar than that of the athlete.
It's not Marianna Tolo racing the clock to be fit for her Olympic Games debut. It's not Terry Campese trying to take the Canberra Raiders back to the NRL finals. It's not Callan Ward hunting his first AFL grand final appearance after watching his teammates get there without him.
It's the voice rarely heard, the knees still in tact. It's the person there to witness the draining rehabilitation phase and the seismic mood swings.
It's someone like Canberra-based physiotherapist Tim McGrath, who is behind "Pitch Ready, the gold standard program designed to provide athletes with definitive individualised and progressive information.
McGrath holds a PHD in Rehabilitation of the ACL and return to sport, and his goal is to fast track recovery timelines - which often extend to about nine months - and mitigate risks of repeat injuries.
Pitch Ready is described as "the gold standard" in injury reduction strategies and rehabilitation analysis.
Built on cutting-edge data science, Pitch Ready enables in-house testing, submission of results and access to athlete testing reports via individual user portals.
McGrath's team specialise in individualising return to play guidelines for athletes following ACL and other lower-limb injuries and building injury reduction strategies.
The data science is the culmination of 10 years of research and development, and was last year short-listed in the Yahoo Sports Technology Awards in London under the category "Best Technology for Athlete Welfare".
McGrath has worked as a physiotherapist for the ACT Brumbies, St George Illawarra, in rugby sevens, English rugby and the AFL. He has seen just about everything walk through the door for day one of rehabilitation.
Being just shy of 500 tests with players from the likes of the NRL, AFL, Super Rugby, and the English Premier League suggests he will have seen the nervous smile or the fire in the eyes countless times.
Those tests are about producing a body part that can absorb and produce force, but it all comes down to how the athlete is able to put it together under a stressful situation in sport.
"That's probably the holy grail of it all," McGrath said.
"The re-injury rates are pretty high and can often be up to 30 per cent. It's not always just about getting people back earlier, it's more trying to mitigate as many risk factors as possible.
"When you drill down to it, there is a whole truckload of things that can weigh in on re-injury risk. Our point of difference is we drill down to some of those factors that are not necessarily easy to capsule or analyse. Things like biomechanics with jumping and changing direction.
"The other point of difference is I've also got a background in computer science and data science. It's the ability to produce robust data but then also being able to apply it in a meaningful sense.
"It's about being able to communicate on both levels from a data perspective, and interpreting that and helping people to formulate plans that are meaningful."
Raiders captain Campese needs you to narrow it down if you want to know how it felt.
There was the 2010 NRL semi-final against the Wests Tigers. The repeat two years later that left him fearing his career was over. The third soon after his arrival at Hull KR in England.
"The first one was easy," Campese said. "The second one? Torture. I was devastated actually, because I knew how hard it was to get back, and I knew what I had to go through.
"Then the third one, I didn't really have feelings to be honest. I felt sorry for myself for a bit, thinking 'why me?' But it was a completely different feeling altogether, the third one."
McGrath says gender is not necessarily a strong factor in re-injury rates, with Canberra Capitals star Tolo rupturing her ACL on two occasions in 2015 and again three years later. The first threatened to derail her golden ambition.
"I had never been to an Olympics before and it was my dream. Since I was in year five at school, I wanted to be an Olympian," Tolo said.
"I just knew. After the doctor tested it, he said there could be a chance it is something else. A week or so later when the physio called me and gave me the news, I could tell straight away just from the tone of her voice that it wasn't going to be good. She told me it was an ACL.
"It was 11 months out from the Olympics so I knew I had a tough journey ahead if I wanted to make it. That started my determination.
"The doctor when he told me said 'I'll give you five minutes to cry, and that's it. You move on'."
Ward came in for testing this year before being sent away with a list of specific things to work on ahead of his AFL return.
The Giants star returned a month later for a drop jump test, jumping off a height of about 30 centimetres and leaping back up as quickly as possible. Then came a change of direction test, one that can so often be the most nerve-racking.
Clinical testing analyses lapsing in the knee, range of motion, as well as strength, jump and power parameters. The final stage is where biomechanical analysis enters the play.
"The first time I did it, he worked out my knee was coming too far across, my hip was flexing too early. The second time I went back it had improved quite a bit," Ward said.
"What I'm talking sounds pretty complex, but he breaks it down into a way that is really simple and easy to understand. Then he gives you exercises that help the certain thing you might be doing wrong.
"To be honest I can't remember the first time I changed direction. It just built up. I had issues with my tendon in my knee for probably six months of my rehab and it was really frustrating.
"All of a sudden it just stopped hurting and I felt really strong in my knee, and I could cut and change direction and not really think about it."
THE LONG ROAD
Ward had heard it all before. He was bracing for those tough days, days when he would want to throw in the towel because "this is too much".
But for a player regarded as one of the most inspirational leaders in the AFL, that moment never came.
"Obviously you have some tough times, but the biggest thing I have realised is football is important to us footballers and everyone involved in an AFL club, but there are more important things out there," Ward said.
"I have probably realised if I'm not playing football, it's not the end of the world. When I was younger I never wanted to be injured because I didn't think I could handle it, but you get a different lease on life and you realise family and friends are more important.
"There are things in life more important than playing football. It's a huge part of our lives but it's not everything.
"With an ACL injury, and with all injuries, you make small steps in your rehab. You have to break everything down.
"Yeah, it's a 12-month recovery period but if you break it down to a few weeks at a time or a month at a time, it doesn't really seem that long. It actually went pretty quickly which is good."
"Definitely excitement," Campese said of the feeling before his 2011 return, nine months after his first ACL tear. Back on home turf, he couldn't wait. But "I came off the bench and only lasted a couple of minutes and tore my groin off the bone."
So that was it for 2011. One game. Naturally he was nervous ahead of his comeback from the second tear, but that went off without a hitch. The third?
"I tore my hamstring in the first game back. I was excited leading up to it and then deflated when that happened."
Today the Queanbeyan Blues player-coach is content to play until his knees are gone. Tolo? She has gone on to lead the Canberra Capitals to consecutive WNBL titles in a remarkable turnaround.
She steps onto the court without a hint of trepidation. She knows she has left no stone unturned in her recovery, just as Ward has.
"There was always a light at the end of the tunnel knowing I would eventually get back and play again," Ward said.
But Ward's tunnel is different to the one Campese went through, and the one Tolo went through. Because no two athletes are the same, which is why Pitch Ready is described as the gold standard.
"There are definitely common themes across the board but you've got individual variances across sports," McGrath said.
"A rugby union prop is going to have a very different demand within their sport to an AFL player or an outside back in rugby league. Drilling down to that individual level is quite different when you are trying to offer meaningful insights for their rehab."
As an athlete's search for the ultimate success goes on, so too does the research behind the scenes, from that face you rarely see.