I should have reworded - I got used to no AC in elementary schools in the early 1970s. Pre 1960 about 10% of population had AC so most I assume a number of folks adapted to the conditions at that time. When you experienced this when you were young perhaps to improve the situation - adjust schedules due to the heat , use circular fans to help move hot air. One thing that helped me cool down when I lived in an apt with no AC was having a fan on high blowing in front off a bowl of ice cubes for makeshift AC.m, hydrate with cold water ,just a few things that came to mind . Not the greatest contraption ice with fan but it helped.