> Nobody lifts weights or does labor like they used to.

I'm fairly sure _vastly_ more people lift weights today than in the 70s. At that point it was, well, not niche exactly, but you didn't have anything _remotely_ like the number of gyms around. Can't offhand find figures for back to then, but apparently it's up ~60% in just the last two decades.

I guess you missed the part about physical labor in my comment.

You're looking for an answer via a really poor proxy. Lifting weight is lifting weight. Gyms are more popular because of the lack of sensible alternatives for a comprehensive workout. Any data you find about them will also be biased towards the recent decades of office work and working from home. Is there any way to tell if gyms are even picking up the slack? My guess would be overall exercise is down, even for those who go to the gym regularly.