When I was a younger potter I used to take rejection as a challenge. I always assumed that it was a sign of something I wasn't doing -- something lacking in my work and/or vision -- and I would redouble my efforts to "fix" it.
As I've aged, I've lost some of that youthful optimism. Now I deal with rejection by setting what I hope will be ambitious but realistic goals -- some of those goals focused on the craft aspect of business, and some of those goals focused on the business aspects of my craft. In a business model with so much out of my control (juries, trends, weather, etc), I take some encouragement in what I can do -- what I can control.
I try not to find others to commisserate with. It's a horrible temptation to do so, but it tends to bury me deeper in discouragement. As comforting in the short term as it might feel, it just can't be a wise practice to find encouragement in the similar failings and discouragements of others.
And just when one finds comfort in those fellow sufferers, that's when they find their way out of that "slough of despond", leaving one even more discouraged.
Instead, I try to look to the successful and see what they may be doing differently. If it's something simple that I've overlooked, it will have been worth the learning. If it's something inherently "them" that could never be a part of me, I still try to see if there could be any correlation to my view of the world (sometimes worthwhile parallels aren't immediately obvious).
And, as in my youth, I try (though I find it harder now) to be willing to change. And change anything.
Good songwriters don't necessarily think of their songs as ever finished. That is -- even when a song is complete enough to be worthy of recording, it is still fodder for revision -- and each revision can be good, meaningful, vital.
I can sometimes get so entrenched in something that "works" on some level, that I fail to see that it's not "done" -- it's just another step on the long journey.
Discouragement is goal-oriented. Living is journey-oriented.
That's how I see it, anyway