It's 107° in TX. I was out riding for about an hour on my emtb, and came back without breaking a sweat (not totally sweat-free, just not feeling drops/bullets forming). I didn't seek to crank up the AC or fan once home either. I adapted quickly to the climate, unlike my coworkers, who seem to need to vent their misery. I just have a lot of exposure to the outdoors, since it's my "daily driver."
On a related note, the emtb has eliminated much of my "fitness anxiety" thanks to the motor and all the bike commuting, so I don't care what it weighs as long as the parts satisfy my needs. This explains the big fenders, big saddle, reflectors, bike lock, and other things my bike has. That and just going for strong and cheap stuff, like 600+g rims, 420g handlebar, etc. I got a set of 145mm cranks and cut my hbar to 735mm since I was tired of banging into stuff.
I also regularly hauled 20+ lbs of groceries 10+ miles and occasionally hauled big 45+ lb boxes on my back (an actual bike box containing an MTB I sold), cutting out car trips.
I did 4+ hour epics spontaneously, without any water, food, or other supplies, in plain clothes. The battery itself was like my supplemental fuel source that diminished my body's need for it. That said, I've regularly done 3-4 hour rides without water on at least a weekly basis, so going a little further, riding to some random peak on the horizon, wasn't that big of a deal.