"It was the mental strain, the sense of being apart, adrift, incomplete, surrounded by those constant, early-morning reminders of what he used to be, and where he wanted to be," Rory Smith wrote in the New York Times while discussing Ilkay Gundogan's road back to fitness in September of last year. “The general feeling,” the Manchester City midfielder said when describing his rehab, “is of loneliness.”
The Germany international, however, is now back amongst the Cityzens XI; lifting the Premier League and Carabao Cup trophies last season as he put his darkest days behind him. However, there are some who are not as fortunate as the 27-year-old; those who never fully recover from career-defining absences.
"For six or seven years I hated it," Michael Owen revealed candidly to BT Sport at the weekend. "I couldn't wait to retire. Mentally I could do it, but physically I couldn't."
The former England international opened up about how injuries affected his career; how a constant fear would stop him from fulfilling his true potential throughout his time in the game.
However, the ex-striker, known best for his time at Liverpool and Real Madrid, is by far and away not the only player whose dreams were snatched by unforeseen circumstances, with some even having to come to terms with their career's ending before properly getting underway.
So, with that in mind, let's take a look at seven players who were never quite the same after being let down by their bodies.
1. Robbie Fowler
"I could have gone on to become the best in the world," former Anfield great Robbie Fowler insisted during an interview in March last year.
However, the Liverpudlian - who scored 183 goals in 369 appearances for the Reds - was not the same man after a derby day collision with Everton goalkeeper Thomas Myhre in 1998.
"It probably did change me," he added. "I remember waking up from the operation with a big gap in my leg. I did every ligament in my knee, and I can remember thinking I was finished."
Although not 'finished', Fowler was certainly not the same potent frontman which had terrorised defences across the Premier League and Europe the five years previously.
Between October 1993 and and the end of the 1997 campaign, the ex-England international scored the fastest ever hat-trick (a record which stood for 21 years), won the PFA Young Player of the Year Award twice, and became the only player across Europe's top five divisions to score over 30 goals in each of his first three seasons.
After the injury, he was never the same.
2. Ledley King
During the final years of his Tottenham Hotspur career, Ledley King's pre-match routine would consist of little more than a light jog around the club's old Chigwell training pitches before taking a glance towards boss Harry Redknapp.
“He would give me a thumbs up or a thumbs down,” the former Spurs manager recalled. “And, if I got the thumbs up, I would think ‘great, we will win tomorrow’.”
The 71-year-old's comments are almost as conclusive as you can manage in terms of how significant King was to the north Londoners, even despite his constant plague of knee issues.
However, unlike Fowler, Owen or Gundogan, the former England international's issue did not cut him down in his peak, but went the journey with him.
"It's amazing that I played as long as I did when I think back to that game at Pride Park," King said in 2012 after revealing just 30 seconds into his full debut in 1999 he knew he was in trouble.
"I just about finished the game but I needed an operation on my knee which kept me out for six weeks. I've been having operations on that knee ever since. You could say that was the start of the end and it was only four days after my 19th birthday."
Without King in the frame, England's centre back pairing went on to become John Terry and Rio Ferdinand during the time defined as the country's 'Golden Age' - although Sam Allardyce, while in charge of Blackburn Rovers, insisted the Spurs man's talents eclipsed both.
“Harry Redknapp was saying Spurs wouldn’t get into the Champions League because their run-in against Arsenal, Chelsea, Manchester United and Manchester City was too difficult," he said back in 2010.
“But Ledley played in all those matches in and it was him who got Tottenham through those games even though he’s not fit enough to train. Arguably, he is in better form than Ferdinand and Terry. If he was fit enough I would expect him to start regularly for England.”
3. Fernando Torres
"Not good enough" were Gary Neville's words towards, at the time, Chelsea's Fernando Torres after a drab 0-0 draw with Arsenal in 2013 compounded the west Londoners to an entire calendar year without one of their strikers netting away from home.
A then-record-breaking £50m fee saw the Spaniard leave Anfield for Stamford Bridge in 2011, although, unbeknown to the Blues hierarchy, they were not capturing the player who had taken the world by storm at Liverpool following his arrival from Atletico Madrid four years prior.
In 2007, his first term in England, El Niño notched 24 goals from 33 top-flight appearances and went on to score the winner for Spain in the 2008 European Championship final. By doing so, he became the first Red to net over 20 times in a season for the north west club since Fowler over a decade earlier.
Yet, those 33 showings, somewhat tellingly, would be the highest number he recorded in a season while at Anfield, as injury began to take its toll.
Despite absences enforced by groin, hamstring and ankle issues, Torres continued to score goals. However in 2010, on the back of seemingly overcoming his aforementioned issues, a cartilage problem in his right knee - which required surgery, twice (one of which ended his campaign early) - became apparent.
After returning from rehab the first time around, the usually so formidable talisman scored just six goals before having to go under the knife later again that year. And following his move to Chelsea less than 12 months later, his form refused to return altogether.
4. Owen Hargreaves
“He has demonstrated that he can play in a top team. I didn’t think he would be so cool and self-confident,” were the words muttered from Germany and Bayern Munich legend Franz Beckenbauer's lips after Owen Hargreaves' exhilarating, beyond-his-years performance against Real Madrid in the 2001 Champions League semi final.
Four minutes was all it took for a 20-year-old Englishman - who had never played in the Premier League - to stamp his authority on club football's biggest stage; dispossessing the world's most expensive player, Figo, before teeing up Giovane Elber to score.
It was in 2007 that the beginning of the midfielder's tale of woe began, as Hargreaves finally secured a move to Manchester United. Despite winning the Champions League trophy against Chelsea in Moscow in 2008; featuring for the entire 120 minutes and netting the Red Devils' fourth penalty, too, things never really happened for the Canadian-born distributor at the north west club.
Injuries over the following years meant that Hargreaves became a luxury no club could afford to take a gamble on.
In the end, after securing a year's contract with Manchester City via YouTube training videos but making just four showings, Hargreaves opted to hang up his boots at the age of just 31. And although they may not want to admit it, with him in the side, things could have been so different for both United and England.
5. Jamie Redknapp
Jamie Redknapp attempted almost everything to keep the light of his career burning during his latter, injury-riddled years.
"I had a passport stamped with unlikely destinations that were filled with promises," he wrote in 2009. "I went to America, to Germany, to Italy and to France, where I travelled with a knee injury and the osteopath wanted to take my wisdom teeth out. Apparently, it is to do with clear pathways around your body.
"I saw Diego Maradona's physician in Naples once, but that didn't help. I went to Germany to see Hans Muller-Wohlfahrt, who specialises in injecting extracts of cockerel crest into your knee.
"Yes, I went to see Eileen Drewery, too. Why not? She was promising to help me and, for a while, it felt as if she was making a difference. I had a broken ankle and it started to ease. She talked of 'cleansing my aura'."
However, nothing seemed to hold the answer. The now-TV pundit realised his dream of top-flight football in 1991 after he left old third division outfit Bournemouth for Liverpool.
A knee issue, which required surgery, effectively marked the beginning of the end for the Englishman, as shortly after his return to action, following months of rehabilitation, another issue surfaced.
The second problem brought with it the curtain on his time at Anfield. Tottenham Hotspur offered new surroundings and a rebirth of hope. But despite his best efforts, Redknapp was confined to three further years of hardship - with appearances becoming rarer than spells on the sidelines.
And after just a year at Southampton following his stay at Spurs ending, the once so influential Redknapp called time on his career after suffering his first and only relegation at the age of 31.
6. Marco Van Basten
"After three years of pain, I wanted a normal life again," Marco Van Basten, similarly to Owen's candid admission, stated in an interview in 1996. "Just imagine feeling pain every minute of the day, somewhere in your body. And that for three years! It dominated my life."
Before the pain, scoring goals dominated the Dutchman's life. Netting 276 times in 373 games at club level between Ajax and AC Milan, at one point, the former Ballon d'Or winner was the most feared frontman on the planet.
22 separate titles with the two clubs, and also becoming one of only three players to win the European Player of the Year Award three times, puts Van Basten in esteemed company, and, in truth, he achieved more than most while failing to see out his peak years on a football pitch.
Up until the age of 28, the talisman had the world, quite literally, at his feet. But then injury came.
After persistent niggles, the former Netherlands great was forced to undergo a succession of surgeries. Little did he know that his outing against A.C Ancona - the 90 minutes the medical decision was drawn upon - would be his last in professional football.
Due to the procedures, Van Basten was forced to sit out the entirety of the 1993/94 season. The World Cup that summer had been the player's comeback target; however, after gaining advice from specialists, it proved to be only a pipe dream.
And 12 months later, as the 1994/95 campaign was coming to an end, the Milan sniper was forced to call it a day on a glittering career after conceding defeat to his ankle problems.
"The most frustrating thing for me is not the way I hurt my ankle, but the way I have been treated by some doctors," he went on to say in 1996. "Because the person who damaged my ankle most was not a player but a surgeon."
It is almost difficult to comprehend that Ronaldo; a man who cleaned up in terms of silverware and personal accolades, was not functioning at his full potential throughout his career, although that was indeed the case.
352 goals in 518 competitive games and 14 trophies during his stay in Europe, alongside netting 62 times in 98 showings and winning four trophies - including the 2002 World Cup - while part of the Samba Boys' set up; there were not many in that period of time who could match the Brazilian both on the pitch and in the trophy cabinet.
However, when looking back of his career, it is the time spent at Inter and Barcelona which register most. A decade of frontline dominance, where O Fenomeno's bullish brilliance allowed his to soar among the world's elite.
Yet, the final chapter - his AC Milan, and then Corinthians days - are almost stricken from the record; as though football does not wish to tarnish such a great with mere mortal crises such as injury.
But that was to be the case during the final three years of Ronaldo's career, a time when a knee problem - which had persisted throughout his footballing life - finally became too big a burden to bear.
"It's very hard to leave something that made me so happy," Fenomeno stated in a teary farewell two years after leaving San Siro for Brazil. "Mentally I wanted to continue but I have to acknowledge that I lost to my body."