Finishing a song (and being happy with it) is like getting someway up a mountain or hill. Our lives are full of physical and mental mountains and with each step upwards we shed unnecessary bits of ourselves to become who we truly are.
As Kurt Vonnegut said in a letter to high school students "practice any art, music, singing, dancing, acting, drawing, painting, sculpting, poetry, fiction, essays, reportage, no matter how well or badly, not to get money or fame but to experience becoming, to find out what's inside you, to make your soul grow"