In fact, according to a recent scientific study, overall levels of happiness decline from one's teens until one's 40s and then pick up again until they peak in one's early 70s.

事实上，据最近一项科学研究表明，所有快乐水平在少年时期至40岁之间会有所下降，而在70岁时达到顶峰。

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That's in the one decade of the teens.

迁移持续了十多年

耶鲁公开课 - 美国内战与重建课程节选

If anything the movie may serve to introduce a new generation to a book that is best read for the first time in one's late teens or early 20s.

FORBES: Political Capital