Yesterday, at my wife's suggestion, I tried swimming as a non-impact form of cardio cross training. It may be something for me to pursue.
I'm not a person who loves being in the water, though I've been a swimmer since I was a kid. My swimming was complicated by my continuing shoulder pain--doing the Australian crawl was impossible, so I did the breast stroke, though that was also a bit of a strain. The thought occurred to me today I could even just get a half-board and kick to do my laps until my shoulder is healed.
I wasn't able to do lots and lots of laps, but I was able to do enough to suggest that eventually this could be a great form of cross training that could build my endurance. One thing I'll also have to build is the muscular endurance required to swim, not just cardio endurance.
The biggest limitation on swimming is getting to a pool. But it would be less expensive than a gym membership.
I'm thinking I might be able to swim once on a weekday and then again on the weekend--probably Sunday, given my martial arts classes on Saturday. Twice a week wouldn't make me an Olympic candidate--nothing would--but it would be a good addition to my training. And it would be easier on my middle-aged joints, feet, etc.