And at the same time it's rigorous, based on research.

同时又是严格的，以研究为基础。

哈佛公开课 - 幸福课课程节选

There is a lot of research showing how difficult it is to change happiness based on external factors.

很多研究表明,基于外在因素改变快乐很难。

哈佛公开课 - 幸福课课程节选