Any good resource to rediscover the lost art of laughing?

In the same way we have lost the art of breathing, we seem to have forget how to laugh. I remember the silent generation laughing easily and often, something have been lost since. No wonder people are so tensed & depressed.

As highlighted recently by one of the Monty Python co-founder, the culture might have a part of responsibility. But I do not believe this is the only explanation, there seems to be something deeper.

Do anybody know a good book or resource, to explore & rediscover the art of laughing?