On Your Mark, Get Set, Get Set…

I am a new scholar and for the past year I have been wanting to write a novel.
I realized only now that I was standing on the mark, I would get set, and then I would keep getting set, rather than go.
I would decide I would do these many words and schedule it on my calendar and the day I need to GO! for it, I would suddenly think, ‘It’s totally too much too soon, I need to redo the plan, make it more doable for me, rewrite it, and then I get set again and again.

How will I know if I truly set a too high of a ‘race’ goal for me or it is my reptilian brain?