Fortunately I've never been hit with heat stroke or heat exhaustion, but I got to see a lot of it in action when I went through Marine Corps officer candidate school about 20 years ago during July in Quantico Virginia. They really drilled into us the importance of water, water, and more water when exercising in a hot environment. If you have a true heat stroke with no one around to help you then you'll most likely die. What motorseven most likely had was heat exhaustion, which is no laughing matter either.
The corpsmen used to keep those cheap plastic baby pools filled up with water and ice for the victims, and there were usually a few that got to visit them every day. If you went down for heat then they'd toss you on a stretcher and dump you in the ice water pool as quick as they could, at the same time pulling down your drawers and shoving a rectal thermometer in you to get your core temperature. We called the thermometer the silver bullet and the indignity of having that thing used on you was enough to make you drink your water. If you went down for heat once and came out all right then they'd spray paint a big orange circle on the back of your PT shirt. If you went down again then you were done, they'd rule you NPQ (not physically qualified) and send you home. It's ugly seeing guys fall out for heat, they typically start uncontrollable spasms. We had one guy who's core temperature got to 106 and they couldn't get it down quick enough, he had pretty severe brain damage I was told. I wasn't there when it happened, but they had another guy die from heat stroke that year.
Good advice given has already been given here. Drink plenty of water, avoid the heat of the day, and take frequent breaks. You might end up with a headache from it, but if I were on the verge of heat exhaustion I'd hop in a cold shower as soon as I could. What's happening is your core temperature is elevated and you need to get it down fast.