So people in concentration camps who werent enjoying it just had a bad attitude?
In addition, consider the story of Admiral James Stockdale, who was kept in a P.O.W camp in Vietnam for 7 years. His memoir explicitly mentions Stoic philosophy as having been key to his ability to endure.
“Everything can be taken from a man but one thing: the last of the human freedoms—to choose one’s attitude in any given set of circumstances, to choose one’s own way.”