Maybe you're focusing too much in "thinking about writing" and not actually writing. Don't think about it as a task or a chore, do what really inspires you, have some fun and then you'll feel the need to write :)
True glory consists in doing what deserves to be written; in writing what deserves to be read; and in so living as to make the world happier for our living in it.
Pliny the elder
I think you are right! I think: "I must to finish it yet! I must! I simply must! etc:( "