I think we often forget the reason we started writing in the first place. I know I often get caught up in the details of "is it good enough?" It may not be, and since I'm trying to take writing as a serious career choice, I have to work for constant improvement.
Here's the thing, I started writing becasue I love it. It should be the reason I'm still writing. Because writing should be fun. If you're not enjoying it anymore, is it worth it? (BTW, your answer should still be yes. You have to hope you can get back to that happiness at some point.)
So how do we do it? How do we remind ourselves that writing should be fun and that our writing will be better if we believe in it?
I don't have the perfect answer for everyone, but my first thought is that we all need to be reminded about how fun writing can be. If you're in a slump, try writing something without thinking about the technical. Go crazy, let your imagination take over and don't worry about anyone reading it, just let the story take you where it will.
You may find that your mind is a bigger place than you first thought it was and that rambling can actually help you apply creative technique to your writing. So write to enjoy, and when you're serious remember the good things and stop thinking your writing is crap!
I've read plenty of flash fiction from my followers and I know you all have real potential backing you up, so stop moping and start writing!