There is a lot of controversy about

https://my.clevelandclinic.org/health/diseases/23920-athlete...

like there's no doubt that exercise overall is good for you but if you're the kind of person who regularly runs marathons and does the training you are at higher risk of A-Fib and you may have all kinds of abnormal findings with the stethoscope, echocardiograms and such and... you might go to one cardiologist and they will be all freaked out and another one will think it's a nothingburger. I've been told I shouldn't do more than an hour of cardio a day: like back in my time in the wilderness when I was trying to invent ChatGPT 10 years too early and doing a gangbusters job filling the top of a sales funnel but never making sales, doing twice that helped me keep calm and sustain the effort.