The 27-year old's impressive performances this season were capped with a call-up to the Germany squad for the first time in two years.
He has described it as a 'fairytale' after his emotional breakdown in 2010, and counts himself lucky that he did not follow the route of his former colleague and friend, Robert Enke.
"I had to be careful that I do not fall into a depression," he told German magazine Star during an interview.
"Robert Enke and I were very similar. We were both very sensitive and hated the pressure that was put on us. I was so, so scared that I was going to follow a similar route to him.
"I suffered from many injuries and I had too much pressure on me. Whenever I played I never felt fully comfortable and it affected my head."
Adler continued: "My life used to be very focused on football. I have noticed that this is not good, and even counterproductive for me. I have learned to separate work and pleasure, which has been beneficial."
Robert Enke took his own life in 2009, aged just 32, after struggling to cope with the loss of his daughter in 2006.