Then the problem is not the heat, but your fitness level, which regular biking, jogging will improve. It did for me. After about 20 years of no exercise, just sitting in front of a computer, I decided last November to start exercising (jogging. Bad knees make biking a bad idea)

My 1st day out jogging, I could only go 0.5 miles non-stop before I almost passed out. Today I can do 5.5 miles non-stop. My cardiovascular system is in the best shape it has been in a long time. And I'm almost 60.