Why is it i can't stand the heat and sweat easy when others cope better?

I see you r from the: UK.It doesn't normally get hot there,does it?Here in Dallas,Tx,it really does.There r a few things that make one more intolerant of heat.If you are not aclimatized,by living in a generally cooler environment,it can take a whole season.If one is hyperthyroid or has suffered Heat Exhaustion or Heat Stroke,you can have heat intollerance.Also,the older we get,our bodies become less efficient at coolin