More than any other torment we may undergo in this life. So says the first chapter of The Four Last Things.
I agree that of course dying from a long sickness, or from any sickness, will probably be very painful.
But what about the people that die instantly? From a bullet to the head, a car crash, in their sleep, and all the other ways you can die instantly?
And what about all the Saints? They all suffer this pain when the soul separates from the body?