Originally Posted by bonsai
You still need the motivation tho.
There's lots of other ways to do aerobic exercise that don't involve impact on your joints, but if you're doing all this exercise in your garage then I really don't see where you're going to get the benefit? Its boring as hell.
I don't exercise because it supposedly makes me healthier, I do it becuase it gets me outside and completing a run/bike/swim provides a lot of satisfaction no matter how hard or easy it was.
Oh and If you're getting injured running then you really need to look at your technique, work on it and then slowly ramp up the distance. Technique is more important that footwear.