If you want to spread happiness, "Be the change you want to see in the world." By example.

如果你想传播快乐，“成为你想在世上见到的改变“，以身作则。

哈佛公开课 - 幸福课课程节选

But ultimately, the best way, the optimal way spreading happiness is to work on your own happiness, because then you are leading by example.

但最好的方法，传播快乐的最佳方法是努力争取自己的快乐，因为那时你就成为榜样。

哈佛公开课 - 幸福课课程节选