The song is actually really sad ... First, of course, because of the text:
... "I hurt myself today, to see if I still feel, I focus on the pain, The only thing that's real, The needle tears a hole, The old familiar sting, try to kill it all away, But I remember everything "...
Here someone settles with himself and his life and wonders what has become of him. In life you do not do everything right, because running a lot out of hand ...
But above all, this song is so sad, because no one else could sing as good as Johnny Cash. His voice is inimitable sad in this song, incredibly full of emotions, thoughtful, and unspeakably violated only.
Only makes his extraordinary voice "Hurt" for the song, which he is supposed to be: cry beautiful!