There are times in a writer's life when they'll seriously doubt whether or not they should be writing. It happens to all of us, and it's usually around the time you realize just how long and hard you've been working on your craft without getting any closer to that elusive publishing deal. There isn't a set time or place for this doubt to creep in. It may happen after the third or fourth revision of a query letter, perhaps after giving up on one book and starting a completely new one, or it may just happen a month or two after your agent sent your manuscript out to the publishing companies.
So what do you do when you doubt yourself? Personally, I take a long look at why I wanted to be a writer in the first place: to entertain. I don't want to get published for the notoriety or fame (of which there will probably be little until I put together a couple bestsellers). I definitely don't want to get rich (a very difficult goal to reach as a writer, anyway). I want to give people something fun to look forward to when they have a long, difficult day. I can still remember some of the books I read as a young boy. I remember how much I enjoyed going off into the land of Narnia, Middle Earth, outer space, the mid 1800s, and on and on the list goes. I remember reading those books and getting inspiration for my own stories. I wanted to sit down and write, to create a world as interesting and unique as the world I read on the page.
Life can be hard and depressing. I always wanted to write stories that gave people a distraction. Maybe it would teach them some kind of moral lesson in the process, but I don't intentionally put lessons in any of my books. If the reader gains some sort of wisdom from my story, it should only happen because something I wrote highlights a lesson they learned some time in the past, but shows it to them in a new light. Or perhaps my characters deal with a difficult situation in a way that some people might not normally consider. Regardless, at the end of the day, I want my books to bring peace to the reader. A temporary escape.
This is my passion, and this is why I get up (almost) every morning to sit down and write. Even when I don't feel like sending out another query letter.