Working in the heat can be as extreme as the cold, we don't work in -5 very well, but 30+ can be as difficult physically
Sadly when we get older it gets tougher and some just cope in the heat better than others do, When I was younger never noticed it hot or cold.
now I notice heat and cold a little more,
I tent not too eat much or drink much when working prefer hot cuppa tea on hot days might take 1/2 litre water
For me it's a hat, sun protection if its about 28-30 apart from that I don't, I'm not a fan working in the heat but I'll work 8-2 when hot hot maybe 3 but I prefer to get done and get out of it