What you want isn't always what you get and this leads to a set of reactions to cope with the fact that pleasure isn't always there when you want it either by planning how to satisfy your desires or planning how to suppress them.

世事总难以尽如人意,快乐并不总是在你想要的时候得到满足,你只能通过设法满足欲望,或设法抑制欲望,来应对这样的事实。

耶鲁公开课 - 心理学导论课程节选