Most of us had them at least at one point in history.
Even when you don't call yourself an Artist (I usually don't).
Those moments when someone leaves a not so nice comment on your Photo, the time when you don't sell scrap for weeks, the moment when one of your pieces gets declined somewhere.
Those are the moments we want to go hide, roll up our tents and camp in the desert for a while, nurture our hurt, blame the mean people out there.
Don't waste you energy on those things.
Turn the table and use that energy for new venues, new creations. Or simply go out and play for a while, be happy, enjoy Life.
I know, it's not easy. Just try :)