Certainly, K. realized that today his weariness had done him more harm than any adverse circumstances; but why could he, who had thought he could rely on his body, and would never have set out along this path unless he had to, why could he not tolerate a few bad nights and one without any sleep, why did he get so uncontrollably tired here of all places, where no one got tired, or rather where everyone was permanently tired without it affecting their work at all, indeed it seemed to help them do it? The only conclusion was that theirs was a quite different kind of tiredness from K.'s. Theirs was no doubt a tiredness resulting from work done gladly, something that from the outside looked like tiredness, but was in fact an indestructible peace and calm. When one feels a little fatigued in the middle of the day, that is part of the normal happy course of the day. For these gentlemen, thought K., it's always the middle of the day.

The Castle by Franz Kafka