Speaking of Biking . . .
I don't know if I mentioned this earlier, but I've added bicycling to my own exercise routine. I still love rollerblading, but it's so weather dependent (you want the path to be really dry and relatively clear of twigs and leaves, etc.) that I was losing too much outdoor exercise time to weather. Yes, I walk Captain Jack every day, but that's not the same thing.
Regular bikes hurt my back, but last winter I took advantage of a sale to buy a recumbent bike. I love it! There was a definite learning curve in riding it: the balance and steering feel very different from a regular bike, but after a while I got the hang of it, and now I get out on it at least as often as I do on skates. Here's what it looks like:
It's low slung, and I do feel a little vulnerable riding on the street with it. But practically all the riding I do is on the bike path that starts two blocks from our house, and goes for eleven miles, so mostly I'm off the street, anyway.
If you hear a ding behind you, that could be me! Passing on your left!