I disagree, I think it's more about a person's emotion intelligence. You can choose to be happy even if everyone else around you is not. It might not be easy, but I think it's possible.

Totally agree. One might require to be "in their head" a lot of the time to not get swung down, and enjoy himself such as laughing at his own jokes. To make it possible, one has to be free enough to express oneself (also internally). But freedom of thought and action is on the decline as I've come to observe lately, but that's another topic.