No, I don't want this to seem like a self-help post. That's not the intent. But I couldn't help but be a little inspired by this interview with children's book illustrator Jarret J Krosoczka.
This young illustrator sent out copies of his work and got rejection after rejection. After a couple of years of struggling, he finally hit pay dirt with a major book publisher. Now, there are several lessons in this story but I'll leave you to read the interview to pick them up.