“Be pitiless about this matter of ‘mood'”

I love this quote about motivation vs. discipline when it comes to writing (or anything):

“One must be pitiless about this matter of “mood.” In a sense, the writing will create the mood. … I have forced myself to begin writing when I’ve been utterly exhausted, when I’ve felt my soul as thin as a playing card, when nothing has seemed worth enduring for another five minutes … and somehow the activity of writing changes everything.”

Joyce Carol Oates

Note that Oates has a mile long bibliography.