"What doesn't kill you...."

I find it funny that some people, when faced with tough times, hold on to the saying that "What doesn't kill you makes you stronger" when in fact, the person who said it, Friedrich Nietzsche, died of a mental illness. Ironic, isn't it? So maybe the saying should be modified in regard to the tragedy of Nietzsche's life. It should be "What doesn't kill you makes you insane". Hah.