I just had a conversation with another author that might encourage you: 

Me: How is the writing?

Him: Slow but steady.

Me: Slow and steady finishes books. Remember, you are building muscles like you would if you were training in a marathon. At first you'll ache all over and feel like you'll die after a mile. Eventually you won't even bat an eye at doing a 13-mile run in writing. Just keep going. :)

Him: It feels like dying. Plodding through the first 100 yards. Many muscles to build. 

Me: Hahaha!!! Yes, it does and you'll question yourself 50 different ways with each step...But that first 100 yards is the Valley of the Shadow of DEATH! Read 2 Corinthians 1:8-11 and remember first that our God raises the dead and second that we walk this path with others praying for us. We have them pray so that in the end it glorifies God when their prayers are answered in Him allowing and inspiring you, and all of us, to keep trudging onward!

Me: William Carey, the first missionary to India said, "I can plod. To this I owe everything." He shared that plodding is a painstakingly long pursuit in a singular direction and now you are starting to get what he meant. Keep plodding friend! Keep plodding!

Him: To plodding!