There is also no failure if you look at life, art and creation as a process of learning and growing.
No failure there... just learning.
But sometimes, you just need to stop. Put a play down, and leave it alone for a while.
This is not failure. This is incubation.
Sometimes things aren't flowing and it is actually a good idea to leave a play alone for awhile!
Imbed it in some far away folder in a galaxy far far away, so you can't see it, and start work on something else.
And then, maybe in a week, or a month, or months later, you will be compelled to return to it, and you will see your work from a new perspective and it just might start flowing again. And it just might be amazing.
Success is wonderful. We all love good reviews of our work, accolades from adoring fans, and big parties after an opening night where we have the world in the palm of our hand, but like everything in life, success is fleeting, and most of our lives as writers and artists, is IN PROCESS, in that CREATION place, in that MAGIC place, and, alas, in that STRUGGLE place. But honestly, to me, there are no better, more amazing places to be. Creativity, when it flows, is bliss, fun, crazy, magical and fulfilling, even before anyone else has read it. For you created it, channeled it, manifested it, and you know when it is good. And when you are IN STRUGGLE, it is one inch or one month away from breakthrough, learning and becoming an even better playwright! And that is cool too!
A way to shift away from a FAILURE belief system is to make a commitment to WRITE for yourself. Don't write to be commercial or to make money. Write to write a compelling story that friggin' THRILLS YOU, or makes you laugh, or cry, but write a story that is EXCITING TO YOU.
Then if people like it, if you get good reviews, etc etc. that is just icing on your creation cake.
Telling stories. Bringing stories to life is AWESOME, important, and AMAZING FUN.
So keep writing your plays. Tell compelling stories that THRILL you.