It's the contrast between stress and no stress. The question becomes, well,how much stress do you need to have before you lower the stress?,".

VOA: standard.2009.04.17

And if we lower our expectations, we lower our stress levels and we will enjoy life more.

如果能降低期望，降低压力水平，我们会更享受生活。

哈佛公开课 - 幸福课课程节选