Actually the only time I feel that way myself is if I've had a run-in with someone or tried really hard to accomplish something and gotten nowhere.

But I have a friend who has more and more been down in the dumps. She does see a counselor and gets professional help, but it's hard to not be slightly affected by her lack of enthusiasm myself. I don't quite GET that mentality of not wanting to do anything and not having goals/dreams/ambitions.