That's... pretty much nonsense. Maybe some people feel better after exercise than before, but for the vast majority of people I've talked to, they're mostly ex

That's... pretty much nonsense. Maybe some people feel better after exercise than before, but for the vast majority of people I've talked to, they're mostly exhausted after exercising. Same goes for me. And yes, I regularly exercise significant chunks of time at 80%+ of MHR. And yes, I've done it for extended amounts of time, too. I've done half marathons. I've run somewhat decent times for my age. I was bored out of my skull while doing it. I certainly didn't feel a big endorphin rush.