I'm going to say no on "same cardio" point. The last 4 years I was only doing cycling for cardio. Could be out for many hours before I felt the burn that I do running.Yeah that much running is bad for you.
Stop running and get a bike. Same cardio but with almost no impact on your joints.
Wasn't like a new thing, I ran cross country and track in high school.
Added running and rowing last year, running is both the toughest form of cardio and toughest on body. I'd say rowing is the second toughest on body unless your form is essentially perfect.
Worst part of biking is the drivers. I've had 3-4 close encounters over the years. My mom has actually been hit before.