The younger generations are far less physical than my generation, and they shift from playing outside onto gaming consoles at a very young age. This impacts their bodies directly, but there is also a change in diets, with much more sugar, which also affect hormone levels. This likely affects their moods also, right?
They not only do not do as much exercise, but the problem is that now, some of them don't even walk daily as some work from home and others use electric skates to move around town. Add the awful diet most of them eat and we have the perfect mix for a health nightmare generation
Just imagine if there were step counters back when we were kids.