"Ego is the enemy of the imagination.
Anything that you think about writing, when you are not writing, is a product of the ego and is absolutely wrong. 100%, all the time wrong.
And if you take a step back and think about how much time you spend trying to purify yourself in order to get ready to write, that’s like 95% of the time. And the reason for that is the Ego has a stake in perpetuating the behavior that you’ve already engaged in.
We do not think our way to right action. We act our way to right thinking.
So what I do is I start writing. If I think about my writing before I start to write, what I’m really doing is justifying not writing. So, because what I’m thinking when I’m not writing, I’m not writing. so I’m gonna find a way to keep not writing. So what I say is I don’t have the idea, it’s not fully realized yet, my pencils aren't sharpened, I don’t have the right notebook, blah blah blah, it’s 11:45 time for lunch…"
-David Milch (taken from Story Fanatic)
I'm sure the same can be applied to drawing. This is definitely something I suffer from. Thinking about drawing WAY more than actually just drawing.