As someone who has suffered numerous episodes of heat exhaustion synacope due to having to walk to work to the point of many ambulance rides to the ER, I can clearly say that the author of this article can simply go walk a mile in 125 degree heat index every day and see how well his "tolerance" builds up.
Or, he can go straight to Hell.
@AnthonyJK Try bringing cold water to drink next time
I did that, constantly.
Yet, somehow, I'd still get fainting spells.
Although, the stress of the job had a lot to do with it as well.