I've always enjoyed telemark skiing until I too, sretched out the ACL in my right knee. Whitewater canoeing, pool, hiking, scuba diving, and photography all fill the gap when I'm not listening to music.
Audio as a hobby
The only problem with audio and music: it a very passive hobby. Of course you could ride a stationary bike or even have sex while listening to music . But then audio/music becomes sort of secondary. So the question, do any of you have an active, non-passive hobby that is the equal to audio/music??? Just curious, or all of you just couch potatoes???