track chick,
I am in a similar situation, maybe we should start a support group. I'm 27, and badly injured both knees being run over by a car 5 years ago. I did actually come back and run for a while but then tore my meniscus 2 years ago. Since then I have pretty much given up. I get my track fix through my wife who is a coach, but I do miss running with her.
I'm not in a lot of pain day to day at my desk job. Running is painful but I can limp through. Anything more dynamic is out of the question. I have quit trying to run for fear of further damage. Sadly I've come to accept that with cartilage issues there's just not a lot that can be done. A snapped femur and might have been better. Maybe they'll have perfected growing new cartilage from stem cells before too long.
I have added in lifting weights and biking, but neither bring me the joy running did. I do both just because I like to feel in shape. Biking can be fun from time to time, a lot of people like it better than running so you might give it a shot. It's being stuck on that seat that keeps me from really getting into it. That and for some reason I'm paranoid about being hit by cars. Lifting is ok, mostly I like the improved strength and appearance that comes with it more than lifting itself. I have had to modify my lifts for my injuries, only half squats with light weight for example.
As you can see I haven't really moved on yet either. I have tried to focus more on my career, but it's just not a true passion of mine.