When I am feeling down about my art, and where I am in my life, I do something that I've never heard recommended. I go find an artist whose work is in the same vein as mine. Someone who is more successful than me, but whose work I despise.
I read as much of their work as I can stand, and then I close the browser window, or the book, or whatever media brought their work to my eyes or ears, and I think "This talentless bozo wakes up every day and decides not only to live, but to keep producing their horrible art and inflict it in on the world. And people are giving them money for it. And this artist is, if not happy, at least content to keep breathing every day, despite all the hexes that right thinking people have put on them. And if this dingleberry gets to continue to live and produce this art that I hate, then there must be a place for me and my work."
Then I go make food, or watch TV, or something that makes me forget their terrible art.
I never do this BEFORE sitting down to create work, I only do it after I get frustrated by work, and I always give myself time to completely forget about before returning to create.