There are some days, beyond the shadow of a doubt, when you wonder why you bother to write. You have crafted and chosen, played with form and structure, created (hopefully) believable characters and placed them in an imaginary world that has a good internal logic and a sense of wonder all its own.
You send the story out... wait a bit... and it comes winging back to you with a 'thanks but no thanks' attached to it.
Rejection is, unfortunately, part and parcel of any writer's life and I have experienced my fair share of rejection letters over the years and been crushed by every single one. It never really seems to get any easier and I think I know why.
Regardless of its actual worth, I am always of the belief that the story (or stories) that I am working on are the best that I can do at that particular point. I send them off with a metaphorical kiss on the forehead and am crushed when others do not seem to realize exactly how wonderful my work is (of course this is not to say that I haven't written some stinkers in my time, but that only really comes with hindsight).
In some ways, though, that sinking feeling you get when reading a rejection letter is a good thing because it means that you actually care about your own work.
As they say about horse riding, the only thing to do is to get back on again or, if you're a writer, to dust the story down (bearing in mind that some editorial comment are useful) wipe that look of shame off its face and send it out into the world again certain in the knowledge that next time the editor will love your story just as much as you do.
Some days are difficult... But then there's always tomorrow.