PS - Why do you think you'd be able to bike, swim, surf, or whatever?
If you can't run that means you're INJURED. Which probably means it would hurt too much to do any of those activites.
Not being able to run means NOT BEING ABLE TO RUN!
I constantly hear comments from other dads (of our kids' soccer teams) that their knees hurt and they don't/can't run. The next thing you know they are out on the field running around kicking the ball with their kid!?! If I could run just 10 feet I could run 10 miles...........