"I also stopped running 7 miles, which is really unnecessary and potentially harmful to the heart and joints"
Source?
Source?
Long-distance running is reported to predict hip joints degeneration. But it does not find out which distance is good and which is bad.
http://www.pponline.co.uk/encyc/heart-attack-risks-are-great...
Such articles state that endurance running (as opposed to sprints) , or any edurancy activity, increase heart attack chance.
No exercise is purported as the greatest heart risk, so perhaps high intensity low endurance is best for heart health? I'd imagine it wouldn't build stamina.