I recall that my workshop leaders were tactful in their ways of acquainting me with my shortcomings as a writer. So much so that I hardly realized they were doing it. I want always to keep that sort of thing in mind when I'm teaching. The way you get better in everything in this life is to make mistakes. Otherwise you're probably doing it right by accident. But you have to do everything wrong before you can really start with some authority to do it right.
There are very few professions in which people just sit down and think hard for five or six hours a day all by themselves. Of course it's why you want to become a writer - because you have the liberty to do that, but once you have the liberty you also have the obligation to do it.
We are made to persist. That's how we find out who we are.
(This picture is licensed under the Creative Commons Attribution 2.0 Generic license. - Mark Coggins from San Francisco)