A psychotherapist must be comfortable to an unusual degree with negativity, because part of what often needs to happen in therapy is for the nay-saying voices to be let out, to say, scream, cry all their pent-up feelings.  To call this “catharsis” is to trivialize it, because nowadays that word implies something like shitting:  getting rid of the waste.  But letting one’s disapproved-of feelings come into greater consciousness and expression is more like the process of working out.  Toxins are released, yes, but muscle is built.  Anyone who has experienced a deep process of psychotherapy knows that one can exit the room feeling like a major workout has just ended.  The muscles here are the self.  The fibers of the self are built and regenerated through rigorous workout, stretching, pulling. lifting, sometimes cramping and tearing.  No pain no gain.