Anyways I've run marathons in the past, but I mostly do strength training now, actually mostly callisthenics. It's less dedication, gives me more of an adrenaline rush and easier to do than endurance training. I don't deny, though, that most of what I've read says that cardio is better if you just simply want to live as long as possible.
If you only watch TV or read while walking at an incline on the treadmill, it's easy to rack up the miles without inconveniencing yourself. I probably hit about 24 miles a week doing this.
reddit post with main study, also comments have HN posts about it and good critiques. interesting stuff.
I've seen the cardio U curve study before too but do not have it saved like I did the strength one.