What cause culture to cry of enjoyment?

What cause culture to cry of enjoyment?
I think it's the body overcompensating for physical strain.
I've laugh for an hour straight in tears, it be a great work out. My abs hurt for days!
Probably something reasonably funny.
We enjoy a saying that anything that go beyond his limit will turn into it's divergent.
Yet, there must be a more logical origin.
Happens to me all the time...apparently whenever someone feel really strong emotions they're susceptible to tears! Doesn't thing if you're really happy or down in the dumps!
So I guess it would depend how each entity reacts to emotion. That was the logical reason...
Now for the passionate one -
I usually "cry" during fits of laughter...during on of those times when something really funny happen, you can't stop laughing, and for some reason and every small little piece sets you off again... it feel pretty good... until your sides set off to hurt! :)
I think it have a lot to do when someone else, is laughing beside you. It makes you guffaw even more watching them, losing it. That happened to me at work. The customers be looking at us like we be crazy. If they only know we were laughing at them. That even made us giggle even harder.
luugfing to much which causes tears its markedly healty and would make you live longer.
sounds close to your just a in good spirits person, we want more people similar to that in this world