[throw20102010]

You missed the point. You don't need to live a long life to be happy. That's you trying to impose your worldview on other people.

A lot of people confuse things that are correlated with being happy with things that make you happy. Being fit does not make everyone happy, it makes some people happy. Eating cheesecake makes some people happy, but not everyone.

What if the things that are correlated with happiness change over time? What if instead of idolizing pro athletes the next generation idolizes pro esports players? Will physical fitness start to see less of a correlation with happiness, playing second fiddle to something else?

I agree that you do need unblocked arteries to stay alive. So increasing obesity may lead to more hospitalizations (and unhappy people that way). But could it be offset by increased well-being in other areas of life?