I see alot of authors lose motivation for a story or stop writing altogether. 

 I wonder why they started in the first place? I think now and again writers/authors need to examine WHY they write what they write or why they feel the need to write.

For me, I started writing in 8th grade. I was a young pervert leaning to the dark side and I just had to get all that stuff out of my head and on paper. Later, it was to get my emotions out. I stopped for a while because...well, life happens.  I graduated highschool, went to college, had a real job, men troubles, children - blah blah blah.

 But I still wrote a little here and there at night as a way to destress from a long day. To keep me from losing my ever loving mind when my relationships went south or I lost a job. I even got REALLY serious with refining my style after a major illness had me hospitalized for nearly a month and feeling half dead for over a year. ( I wrote the 6 Degrees stories during that time.) Writing helps keep my anxieties, anger, and depression at bay.  I stop focusing on my reality and escape into a world entirely of my own making where anything can happen.

As writers we need to figure out why we write.  

I write because I'm happy

Because I'm sad

Because I'm pissed

Because I'm bored

Because something is funny

Because I'm inspired

Because I need escape from reality

Because I hated how something I read ended

Because something I read had no end

Because I want to read something that doesn't exist

Because my brain is cluttered

Because of movies

Because of life

Because I can

Because it's part of who I am.

And nevermind writing for others if it's not a job (and writing shouldn't feel like a job.)  Write for yourself.  As long as you write for yourself you will never lose motivation and someone somewhere out there will love what you write as much as you love writing it.