Standing around feeling sorry for myself was momentarily exhilarating, but I grew tired of it quickly. "That will do," I thought. "I've had my fun, let's move on to something else now." But the sadness didn't go away.

But trying to use willpower to overcome the apathetic sort of sadness that accompanies depression is like a person with no arms trying to punch themselves until their hands grow back.  A fundamental component of the plan is missing and it isn't going to work.