Folks, you are amazing. The comments on this article are overwhelming, in a wonderful way. Some of you have called me stupid. Yes, that’s well established and I’m glad you recognize as much. At least one of you called me a moron (I won’t argue, though I don’t like the term). Many of you expressed concern (I am fine, and thank you). And several of you have shared your stories of frightening brushes with extreme heat. I’m so glad this conversation is happening. We’re all learning something here.

A brief update: I’ve been on several runs since writing this article, including a 4-miler today out in the desert. It was mid-90s and pretty humid. Yes, I had my phone with and plenty of water! I had full confidence I’d be OK, and I was. Absolutely this would be too hot and too far for someone not properly trained for it. But I LOVE running in the heat and I’ve done a lot of it.

I ran really slow, what would normally be “Zone 2” for me (sub-aerobic, when one can have a conversation). My breathing (all through my nose) was controlled, the effort overall modest, but I sweated like crazy and my heart rate was in Zone 3 most of the time (a full-fledged “aerobic” workout, but not dangerous).

There’s some science here: Working out (or working hard) in the heat can feel OK to the lungs and the muscles—it can be doable—but the heart has to work harder to keep the body temperature under control, sending more blood to the skin where it can be cooled by the evaporation of sweat. One can adapt to running (or working) in the heat to some degree, and during this long, hot summer, I bet my body has done some of that. But when you're out there on a hot day, stuff is happening in your body that your brain is not aware of. That's where close monitoring (of my heart rate and running pace and breathing rate) and a heavy dose of caution are crucial.

I offer all this up to let you know: I learned my lesson, and I can see that many of you took that lesson to heart, and I’m glad you did. But I still LOVE running in the heat, and so long as I do it safely and avoid being an idiot, or even a moron, being out there on the open trail is a wonderful freaking thing.