for me, the depression catalyst is usually a feeling that i'm going in the wrong direction in life, that i've made a wrong turn and then feel powerless to change my path, trapped on a life path i despise because it is taking me far from my dreams and where i am continually being asked to compromise my values and dignity. also, a feeling that i am in the wrong place, where my talents are being wasted, and so i feel i've failed myself for making a choice that has wasted so much time.

well, something like that. it's quite hard to explain, and probably i do not understand it completely yet anyway.