Agree with Stik about the painting etc, gardening is good if you enjoy gardening. I'm currently training freediving, but out of the water so, it's just a noseclip and a stopwatch and away I go, but that depends on whether you want to get in to a sport. One person does dynamic freediving, which is underwater swimming distances in a pool, in order to stay fit because it burns so many calories. There's also, underwater hockey/octopush; squash; tennis; badminton; hiking; mountain biking (that's normally cool and hard); CrossFit (see the internet); rock climbing...
Some of the above may need some outlay of money, but not usually a lot depending on what level you want to take something to, or if a club or people can help, which they are normally happy to do. One forum member is training triathalon, which is a combo of fitness skills, and keeps the variety there. So, it really depends if there is something that takes your fancy, that you can really get in to and enjoy. Dancing, as you say, is a good option because you have to be all-round fit for that.
For me, it's an aerobic stepper, a few dumbbells (not a lot), and a noseclip...but I need to get some goggles and a swimming costume before I hit the water