Why does Winston reflect that he was already dead?

Winston reflects that he was already dead because he feels a profound sense of hopelessness and despair in the oppressive society of Oceania. He believes that his individuality and spirit have been crushed by the totalitarian regime, rendering him a mere shell of a person. This realization underscores his internal conflict and the extent to which the Party has dehumanized its citizens, leading him to conclude that true life, with freedom and authenticity, is unattainable in his current reality.