You have to be willing to make mistakes. You have to be willing to put something out there that won't be loved by others. And you have to be willing to put something out there that you may not even like yourself. So much of writing is just the willingness to get it wrong--the willingness to get it wrong and to try again.
I didn't really plan my day today and suddenly I find that if I do want to post today, I need to squeeze in a quickie before I go out. To be able to do that, I have to choose to make the time--even if it is only a ten or fifteen minute stretch in which I can write just a few lines while I wait for my friend. It's really easy to say "I don't have enough time to write something good." The truth, though, is that you can write something good in a short time--and even more importantly, if you practice writing regularly, and you choose to risk mistake or rejection, and you choose to make the time, then you will make the best possible progress in your writing practice.