When I was a kid, a friend of mine and I used to make these really bizarre super hero comics with heroes that were part tree or made out of apple cores or something. Over time, it evolved into more in-depth creations that featured characters with more interesting stories to tell, about things like no girls in school talking to you. Needless to say, I didn't quite make a career out of those creations.
Enough people tell you that your art is terrible, you start to believe it. Same goes for your singing voice and your lack of a six-pack or any muscle tone at all.
So inevitably we grow, we become better at the things we do. We strive for excellence in a vigilant and serious manner. And we fail. Epically.
Life can be frustrating, upsetting, and in some cases utterly humiliating. But there is something powerful in that failure, and I think we should embrace it.