As he stood before Dortmund's famous 'Yellow Wall' and said his goodbyes, Jurgen Klopp knew that he was spent, both emotionally and physically.
Having guided Dortmund to the Bundesliga title in 2010–11, before winning the club's first-ever domestic double during a record-breaking season, the behemoths from Bavaria struck back as Bayern began to take their first steps on the path to eight domestic titles in a row.
However, it's arguable that Klopp's greatest achievement at the Westfalenstadion was when he guided Dortmund to the 2012–13 UEFA Champions League final.
Standing in their way? Bayern. Who did he see Gotze and Lewandowski leave Dortmund for? Bayern.
Klopp famously said this once: "At the moment, it is like what the Chinese are doing in industry: they look at what others do, copy them, and then with more money and players follow a similar path." Who was he talking about? You guessed it, Bayern.
A change was needed and after leaving Dortmund in 2015 as their longest-serving manager, Klopp knew that he needed a well-overdue break to recharge those high-energy batteries.
However, fate had a different plan.
As revealed in the recent BBC documentary Liverpool: The 30-Year Wait, Klopp was on a family holiday in Lisbon when he was asked to replace Brendan Rodgers.
After hearing the news, Klopp's sons were extremely enthusiastic about the potential of their dad managing Liverpool. The wheels were in motion.
Chairman John Henry described the chance to meet Klopp in New York as "one of the most exciting phone calls that I've got during the ten years I've been with the club" and the rest is history.
However, one part of Klopp's appointment that's not known the public was the closeness that he already felt to the city of Liverpool, especially the families of those that died at Hillsborough.
During the BBC's documentary, Margaret Aspinall, Chair of the Hillsborough Family Support Group, told a beautiful anecdote about Klopp's decision to come to Liverpool.
"I met Jurgen in his office at Melwood. I hope he doesn't mind me saying this, that his son came over and watched a game at Liverpool. He went home and told his dad, he said: 'Oh My god, the people of Liverpool are amazing - the way they stick together, the support they've given the families of Hillsborough.' Klopp told me that was one of the reasons why he came, because of the people and the way they believe in what he believes in - and that's fairness and justice. I thought that was really nice of him," said Aspinall.
After waiting 30 years, Liverpool will start a league season as champions of England when they start the defence of their Premier League crown against Leeds United on September 12.