Opportunity Cost
机会成本Every choice you make is also a choice to give up everything else you could have done instead.
说白了就是：选A，就是亲手关掉B和C。不是没机会——是你自己放的。这条我经常犯。
Coined by Austrian economists in the late 1800s; popularised by Alfred Marshall and now a cornerstone of economics and decision theory.
经济学家造的词，说的是人人都知道、却没几个人真的算过的事。名字难听，道理简单。
You spend Sunday watching TV. The opportunity cost isn't just the time — it's the workout you didn't do, the book you didn't finish, the call you didn't make.
刷两小时手机，损失的不是"时间"——是那篇一直没动的稿子。代价要说具体，才会真的扎心。记住这点就够了。
It can produce paralysis: listing every forgone option inflates the cost of any action, making choosing feel reckless and not choosing feel safe.
这条容易用错：把所有放弃的选项全列出来，任何决定看着都亏。结果是不敢动——其实"不动"也有代价。别用它来拖，用它来算清楚再动。