I used to play DDR all the time, and then my mat broke. In the past I was talking Ballet classes as well so I was in shape, but it didn't give me muscles. Dancing is a good way to burn calories, a good cardio workout and a fun way to get your body moving.
Now I try to do the Bad Apple dance whenever I can. It's fast and rather intense. It will make me feel cool in my Touhou costumes as well.
Start out simple it you are out of shape, like twice a day and then do more for longer periods of time.
Stuff I hope to do by the end of the year:
Prism - Original design: Done except for the bow
Akihito Kanbara (Idol) - Kyoukai no Kanata: Need to add details
Drag Cloud - Final Fantasy 7: Need dress, wig and braids
Princess Daisy - Mario: Haven't even started
Bahamut - Final Fantasy 4: I need wig, and to make the wings
The Best Costume Ever - It's a surprise: All I need is the wig!