Goodreads asked H. Max Hiller:

How do you deal with writer’s block?

H. Max Hiller I firmly believe that my characters will ultimately write their own story. I have a very detailed chapter-by-chapter synopsis when I sit down to begin writing, but what I find I have written may or may not follow it. I have learned to remain open to where my characters want to lead me, and so I very seldom run into writer's block caused by own determination to stick to the synopsis.
The few times I have been stumped, though, I have re-read the entire synopsis and then begin editing the last couple of chapters I wrote before I became stumped. Usually this will show me what my mental block is and present a means of getting around it. I always remember that I will be doing multiple edits to whatever I write, so just getting something on paper is all I have to do until the blockage falls away. I usually find what the problem in the story was once I have good material written on either side of the rough spot.

flag