People have recovered from very serious depression. Say to yourself: "If them, why not me?"

It sounds like the psychologist was encouraging you to not feel hopeful. Maybe what he really meant was that overcoming your problem will take a lot of tough effort over an extended period of time. There is no law of the universe that says that you are incapable of putting out strenuous effort. But you can make that true by telling yourself that recovery is just too hard. Why limit yourself, like that?