Obsession
To be obsessed - 1. adjective, having or showing excessive or compulsive concern with something; 2. v. intr., To have the mind excessively preoccupied with a single emotion or topic.
Can’t help but think of George Bernard Shaw: The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man. (Via Mark Hobson)