Want a workout that strengthens muscles that keep you balanced, raises the heartrate, but doesn't raise a sweat? Try riverwalking! I took a class this week and, while it definitely takes some specialized "equipment," meaning a "lazy river pool," I highly recommend it!
The class I took was on a weekday morning, so it was designed for seniors (although some of those seniors were kicking my butt!). It was a half hour of laps in various variations (like forwards, backwards, on the toes, grapevine, and bunny-hopping) against the current of a looping pool and a half hour of water yoga with the current turned off.
I won't be able to take the class on a regular basis, but I intend to go back sometimes and do what I learned on my own.