Many years ago in 1980, I rode a bicycle from Los Angeles to Washington DC. A friend and I crossed the Mojave desert in late July, early August. I have photos of thermometers at gas stations reading about 107 degrees. There were two of us, and we each carried three gallons of water with us each day. Had to blow on it to cool it off to make it drinkable. But I remember being about 60 miles from anywhere, and starting to get that dizzy feeling. I started seeing things, and my peripheral vision narrowed to a tunnel. I saw a tower in the desert, and thought it was a tower from an amusement part I had worked at. Saw it clear as day. I saw buzzards circling in the sky. When I focused on them, they disappeared. Hallucination. We stopped in what little bit of shade of a joshua tree made and I drank a lot of water, and drank some honey (a trick I used to use from my rock-climbing days), even wet my clothes down before hopping back on my bike to get some airflow to cool off a bit. It was really no huge deal at the time, but looking back on it, I now realize how close I came. The thing is that I didn't even care. I would have been content to just lie down and sleep. And I was young and fit.
I was glad to have had a friend with me to urge me on. Heat exhaustion and heat stroke are no joke.