I'm 60....exert myself in heat and humidity all my life....I have no idea why I've never had heat stroke....like the chunnel sized completely clear arteries in my heart despite a love of red fatty meats...maybe it's genetics....I'm half northwestern european...and half polynesian...I've spent most of my life in San Antonio (On and off and on and off...) spent a lot of time in Hawaii....San Diego and Pugest Sound (Navy, Pacific Fleet) Connecticut....I've never even had heat exhaustion....