
I also hear that swimming is one of if not the best non-impact ways of exercising around, except I'm a such a shit swimmer that I never get to try it. Every time I jump in the water I almost drown, ad after only a couple of half drowning laps I'm dead tired.
On the other hand, I also cycle and I find it's great for building up muscles around the hip/knee/ankle joints. If I start getting joint pains from running I tend to feel better after a couple of cycling trips around the hills. You don't realise how damaging running actually is until you do some solid weeks of training

I also find cycling makes me breathe much deeper than when I run, which is a huge positive for an ex smoker like me.