Twain

“I once read the sentence 'I lay awake all night with a toothache, thinking about the toothache an about lying awake.' That's true to life. Part of every misery is, so to speak, the misery's shadow or reflection: the fact that you don't merely suffer but have to keep on thinking about the fact that you suffer. I not only live each endless day in grief, but live each day thinking about living each day in grief.”
― C.S. Lewis, A Grief Observed