I do agree that overly sedentary lives are also an issue.
I'm 70's born and when I was school age few families even had one car let alone 2! It was far more common for school kids to walk or cycle to school, now I see not only kids being driven to school but parents being utterly ridiculous in striving to drop them virtually at the door! As if it'd kill them to have to walk even 50ft!!
I've not had a car for several years now as the meds I was on I couldn't drive on. Even when I had a car dd walked the 1.5 miles each way to
school and back excepting if she couldn't due to her disability which was rare. A couple of her friends also walked it who lived slightly nearer but the majority were driven in even those who lived less than a quarter mile from school! Pure laziness and parents enabling it absolutely no reason why those children needed driven to and from school every day.
Then there's the lack of PE classes, parents who let their kids veg in front of video games/tv rather than encouraging them to either play out or do physical activity indoors either at home or organised stuff elsewhere.
I'll admit I was lucky to a degree as dd is very much an "outdoor cat" and hates being stuck in. (Seriously we were snowed in during beast from the east and she drove me nuts!! Because she was going nuts from it)
When younger she enjoyed gymnastics and dance classes although sadly after dx we were told these had to stop. But she remained (gently) active with walking, cycling, swimming, Aquarobics, occasional recreational dancing. By chance (? Was it really chance or similar backgrounds/parenting) her best friend she made at high school is also from an active family, they're very into hiking, cycling, climbing, camping, fishing etc so the 2 of them regularly head to a local popular "walk" for a potter around and a natter, but their other friends from families that drive everywhere and play video games and watch tv whinge about going and dd and her friend are always like "they're so lazy!" One time the excuse given was wet weather (it was barely drizzling and where we live it rains a lot so they should really be used to it!), said friend had/has perfectly good wet weather clothes and shoes. Dd was like "you're not the witch in oz you won't melt from a wee bit of rain!"
Contrarily I am not naturally sporty and am by nature an "indoor cat" mostly but my mum wouldn't let me just sit and read all the time (which was my preferred activity), I was in guides and a member of another youth group that did lots of nature activities, if the weather was dry outside of school hours, homework and mealtimes/bedtimes we were expected to be out and about, either at the park or as we got older she'd happily give us picnics/pack ups and we'd go off with friends to beaches/woods/parks further from home for the day/afternoon at weekends and in school holidays, cycling miles sometimes, I've just looked up one of the places we used to cycle to regularly and that was 7 miles! Mostly uphill on the way there too!
I've even witnessed parents irritated by children being active (dancing, jumping on the spot etc) and telling them to sit down and be still, or children asking to do things like go for a bike ride and the parents rejecting the idea - with no reason to other than they couldn't be arsed!