Personally, I've found myself in all three of those positions. The interesting thing for me to note is the direction in which each story pushes me. I know that when I let myself feel like I'm just not good enough, I fall into a place that is neither kind nor productive and truly serves no purpose. Even when it has pushed me to try a writing class or seek out books on craft, I've come at them from a place of trying to prove myself. In contrast, when the story I've told myself is that the piece isn't there yet, I've come to the new class or craft books from a place of openness, a place of wanting to understand, to make the manuscript stronger. And I've learned a lot from those stories. But lately I'm finding that the strongest place for me is seeing the closed doors in life as guideposts, pushing me in a direction I might have otherwise resisted. And this ends up being the story that lights me up and sends me forging ahead on new paths.
The next time you meet a rough spot on the road, ask yourself what story you might tell about this that would be useful to you, and leave behind the ones that diminish you. See if you can't find a story that urges you onward instead of one that holds you back. Because the story you tell yourself is the only one over which you have complete editorial control.