I don't find this true with myself. I'm a reasonably extreme introvert. But when working out I thrive on external stimulation, like group rides. When everyone goes for coffee after, I'll skip that. But I despise trainer rides staring at a power graph.

"Athletes can adapt to heat in one of two ways. The first is through incremental improvements in tolerance over time—work out in the heat a little bit every day, and eventually your body will dissipate heat more effectively. The second way is through thermotolerance, which is a cellular adaptation to an extreme heat experience, like suffering such severe dehydration after a run that you need an IV. Essentially, if you shock your system, your body will be able to withstand greater temperature stresses later on..... athletes who train in warm temperatures generally get better at regulating heat by sweating earlier, as Salazar did, or developing a colder resting body temperature. "

My N=1 on that is... no.

I got heat stroke and dehydration in a race a few decades back, and yes I sweat at a very high rate now, and my body temperature is a little lower. But my body seems to just shut down if I try to go hard in hot temperatures. I didn't have this problem before.

So if you train hard in hot temperatures, I think you at least need to be careful not to overdo it. This makes more sense, IMO: " One method of heat acclimation that Minson uses with his athletes is to do hard workouts on colder days or earlier in the morning, and then start training in hotter conditions with less intensity."

It's your mind that has gotten to that point.

Thanks for the advice Ron...this summer seems particularly brutal so far doing something which I thought I was used to...maybe old age.

When I read this..I stopped and stared silently at your words. Not heat related but I believe that you could be on to something here...so simple but I think profound.
I'm an introvert. (INTJ)
I hate any distractions on the trainer...music...unnecessary noise..etc. In this heat I could keep going mentally until it finally killed me.
When I ride outside now...it's normally going around in circles on a 250m velodrome...I much prefer that now to a ride down Highway 1 on a beautiful day...lol.
Practically everyday I steady my cooked body to get off the trainer without collapsing...go lay in a cold shower...and get an ice cold beer.
Roughly 15 mins later I feel like I could conquer the world..lol

Thanks!

I've never tried riding hard on the trainer in hot temperatures, but I learned that riding the trainer in cold temperatures (30s) with a fan blowing on your skin can produce some strange counterintuitive responses. Like high core temperature.

Hot tub "therapy" after races was a fad a few years back. Some pros were trying it, but I don't know if any of them kept it up.