I found that I was immensely discouraged after one of my pitches was rejected. I had submitted a story to [as] on several ocassions, with varying degrees of failure. But the one with Cartoon Hangover just gutted me. We had been corresponding for 6 months straight, like 1-2 emails each, a day, sometimes. When we finally submitted the finished pitch we got rejected within minutes which means it wasn't read all the way through.
I've resigned to just doing everything myself. Hopefully in the coming months I will finally have something to show for it, and to share here.