So in the U.S., it has always been or recent trend on using certain health measurements by private health insurers for discounts/premium payments?

The reality is that a very healthy person could be suddenly quite sick with a terminal, non-curable disease. So what happens?

My father is not overweight (never was, in fact underweight for several decades), no cardiopulmonary nor respiratory problems at all. He is 82, but has prostate cancer. Not curable at his age. He is not "penalized" by the public health care system for having cancer which of course is not caused by smoking. (He stopped smoking before he married my mother.)

He has never taken his own heart rate and wouldn't know it. But his blood pressure has tended to be slow as diagnosed by doctor over the years.

This is why I can't get just measure my heart rate as my only indcator of health, there are real life examples in my own family, what type of lifestyle and diet long term one adopts to have overall good health.

(And when a terminal disease strikes, at least one is not suffering from multiple complications because of other health problems.)