Andres Iniesta has revealed he felt like he could not "take it anymore" as he suffered with depression following the death of his friend Dani Jarque.
Jarque died in 2009 when he suffered a heart attack while on pre-season duty with Espanyol.
The loss of his national youth team colleague at the age of 26 had a huge impact on Iniesta, who felt his passion for life leave him for a period before going on to score the 2010 World Cup-winning goal and dedicating it to Jarque.
"You feel that it's not you, that you don't enjoy things, that the people around you are just people," he said on Antena 3 TV. "You have no feelings or passion.
"You end up feeling empty inside and there is a moment that you realise that you cannot take it anymore.
"I had the ability to see that I needed to see someone to get out of that situation. The important thing is that in that period I never lost the spark."
The midfielder is set to enter a new chapter in his career after leaving Barcelona to join Vissel Kobe in Japan.
First, though, he travels to Russia to compete for another World Cup title and is excited to get underway after their disappointing group stage exit in 2014.
"We have a good team, a good mix of young people and those with more experience," he said.
"We will go with a lot of expectation, I think we had two warnings at the European Championships and in Brazil which means that we have our feet on the ground.
"We will go step by step and we do the things right then we will be fighting for the title."