The first comes from Chuck Wendig and his Terrible Minds blog. I like to think of it as incentive. You know, yes I can so finish my book!(Please note there is a fair bit of swearing in the post, so if that's not your thing, you've been warned.)
Number 18 is one that is usually true for me.
18. Haven’t Answered Any Of The Critical Questions
Ask yourself: what is this about? Why am I writing this? Why will anyone care? Asking yourself some fundamental questions before you write — plus several others while you write — can help keep your nose to the grindstone and allow you to feel settled in both direction and purpose.
Also check out his list of those questions. He's got some really great ones.
The second is totally inspirational. It's about sticking with it when you've got that horrible feeling that you have completely failed at writing the book you wanted to write. It's a great guest post by Sara Zarr on Nova Ren Suma's blog:
I bet you can't guess what it is. Failure. Yep. Go read why. If you've been feeling stuck, you'll be inspired to keep going, I swear.