Just about every day. It may sound arrogant, but the best way to reassure myself about my writing is to go back and read it. More often than not, I feel pleasantly surprised that I actually wrote that stuff. So if nothing else, at least I get some feeling of accomplishment.
When you say "good enough," I can't help asking, "Good enough for what?" Is it good enough to make me a famous, published author? Probably not. Is it good enough to make me a few bucks on Hubpages? Maybe someday. Is it good enough to have a positive impact on another person's life from time to time? According to the positive comments I sometimes get, apparently so. I try to stay focused on that last question, although I wouldn't mind making a little (or a lot of) money.