Seriously, the more you run, the more likely you will need a knee and hip replacement in later life.
Start biking and swimming!
I had issues with my knees being stiff in my early 20s. Now that I've taken up regular distance running the past few years, I rarely have any aches and my legs feel fresher than they did 20 years ago. And swimming is a no go, at least until I have my left shoulder examined, as I likely have a partial tear in the rotator cuff and/or labrum from a dislocated shoulder playing football in HS.
That being said, I plan on doing a 50 miler a little over a year from now
Je suis méchant.