I know a few people who felt Yoga sounded a bit "soft" (I know it doesn't have to be) but for those who want something a bit more physical you might want to look at pilates.
As I say, I know it isn't necessarily easy (perhaps gentle would be a better word), but that is a perception and for those people Pilates might be an alternative.
I am in a pretty good shape, working out and playing basketball multiple times per week. Still, the few times I tried yoga it literally kicked my ass. I've grown a lot of respect for those old ladies doing it.
