The Knocked Up filmmaker admits he has battled inner turmoil ever since he was 13, when he watched his parents' bitter divorce tear his family apart, and as a result he struggles to deal with change.
Mann tells The Hollywood Reporter, "He is a hoarder; he doesn't like to let anything go. He doesn't like if I change the couch or a pillow. It makes him nervous that things might fall apart."
However, Apatow has learned how to better deal with his emotions thanks to self-help books like 7 Habits of Highly Effective People by Stephen Covey, and regular counseling sessions: "I've been going to therapy since I was in my early 20s."
And Apatow's frequent collaborator, Seth Rogen, insists the difference in his demeanor really shows.
The comedian says, "He's gotten a lot happier and more confident. He was really stressed out all the time. And because you are stressed out all the time, you are angry all the time."