It's hard work.
And when you're a mom, a wife, a husband, a father, and/or working another full time job it is even more difficult. Fatigue and stress kill creative energy in much the same way as those bleach cleaning products kill germs - 99.9% gone. Sure there's a glimmer of something there, but it's doubtful there's enough to catch.
Don't get me wrong, it's not a bad life. As matter of fact, it's a great life. But it's work. The fact that we do it home, the fact that we do it on our own schedule, the fact that our bosses aren't standing over our shoulder telling us what do doesn't negate the facts. Work is work. Whether we love it or hate it. Whether we feel it's our calling or it's just something we chanced into. Work. Tedious sometimes. Frustrating sometimes. Fulfilling sometimes.
Why am I saying this?
I've heard people say that writing is easy for them, that they love it so much they'd do it all day, that writing is their calling and God just gives them the words to put on the page. I think that's wonderful, but I think they're the minority.
Most of us struggle sometimes. So, if you're struggling to finish, to polish, or to get that characterization just right, rest assured, I'm sitting at my computer doing the same. You're not alone in your journey and you're not alone in hitting roadblocks and brick walls. Don't let frustration and failure (either your idea that you've failed, or rejection from editors or agents) get in the way of success. Think of writing as hard work. Combine it with passion, drive, and creativity. Those four things together are the beginning of success in any area of our lives.