Viktor E. Frankl
People get used to any unusual situation. They get used to even the ravages of war. While people were sent to the gas chamber one after another, the psychiatrist who was sent to the Nazi concentration camp smiled in spite of himself when he was told that it would be him if there was a possibility to be sent next. Because he had just wanted to escape that cruel place all the time. It was an extreme situation in which he could survive only by paralyzing emotions.
From "Man's Search For Meaning" (new edition, translated by Kayoko Ikeda).