What would I do, if I didn't have to do it perfectly?
A great deal more than I am.
This is a page from The Artist's Way by Julia Cameron. 

Have a look at this page and let's discuss if anyone here has faced this issue.

So, I personally have struggled in finishing music because I'm my greatest critic. 
And I relate to this page a lot.
I think people here would relate to it too and we could talk about how we can overcome this issue or help others.