I live in a temperate climate, where temperature goes up to around 35 degrees Celcius in summertime. I don't tolerate temperatures above ~28 degrees well. To my surprise, I have found that if I go for a short run in the hottest time of the day, that will seemingly kickstart my body's thermal self-regulation and I'll only experience a fraction of the heat discomfort for around ~2 days. If anyone is interested in trying this, be mindful of the dangers of heatstroke and dehydration.