Creating art requires a little bit of faith. Optimism is not required but faith certainly is a prerequisite.
I don't mean to say that creating art requires a belief in god or some sort of religious dogma however it does require faith in the artist's vision and their connection to the world around them. Faith in their ability to resolve problems that emerge as the creative process unfolds.
Sustained creativity whereby the artist creates consistently, requires a level of faith that enables them to release their work without fear of rejection and anxiety related to feelings of insignificance.
All that matters is the process. Faith in the process. Observing and listening for resonance. Transmuting those sensations into art and presenting it to the world. Wash, rinse, repeat.