However,this is more difficult because it is harder to control the diets of people and because they live longer than other animals.

VOA: special.2009.09.01

Not only is it inevitable that you're going to die; not only do some people live longer than others, you don't know how much more time you've got.

你会死去这不仅是不可避免;,不仅有些人活得比另一些人久，你也不知道自己还剩下多少时间。

耶鲁公开课 - 死亡课程节选

Optimistic people, and again, not Pollyannaish detached optimism, but grounded optimists, on average, live significantly longer.

乐观的人，不是指盲目的乐天派，而是脚踏实地的乐观主义者，平均而言，明显更加长寿。

哈佛公开课 - 幸福课课程节选