One way to get your cardio in would be to go dancing. And it doesn't have to be the dance clubs with the young energetic alcoholics. You can get a pretty good workout by taking tango, salsa, waltz and ballroom dancing classes.
If going outside and sweating in front of other people sounds embarrassing there is also plenty of YouTube videos which can help you (some of which are more exercise oriented and some which are more how to guides).\
Another fun thing you can do is join a local flash mob group (singing and dancing in public locations). Like this one at Toronto's Eaton's Centre.
For those looking for more of a challenge they might also try out figure skating and synchronized swimming.