Hamburg's Germany defender Dennis Aogo has revealed his three-week break from football at the start of the Bundesliga season was due to depression.
"At the end of the pre-season, I found it harder and harder to get up," Aogo, 25, told German daily Bild having returned to training with his club.
"I thought it was just a phase and I tried to drag myself through it, but there came a point when that was no longer possible.
"When the body stops working, the problem goes to the head.
"I was depressed and I no longer felt myself."
Having made the last of his 10 appearances for Germany against France in a friendly in February, Aogo played the first two Bundesliga games of the season before he was sent to Innsbruck, Austria, to be treated for an infection.
"I was run down for the first ten days, then the energy and motivation started to come back," he said.
"I ran every day, rode a bike and hiked.
"Today, I can say that I feel really good and that is a great feeling."
Hamburg are eighth in the Bundesliga and their next league game is home to Hamburg on October 21.
Depression amongst professional footballers is a hot topic in Germany after it emerged former national goalkeeper Robert Enke suffered for years with the mental illness before his suicide in November 2009.