Honeybunz, if you're trying to explore, why not join a
BodyBalance class at first? It's a combination of Tai Chi, Pilates
and Yoga done to a mix of really awesome music. It's one of my
favourite classes and it can get quite challenging as well.
Pilates was designed by physiotherapists, I believe. Professional
dancers would practice Pilates as well because it tends to develop
long, lean muscles, which of course, enhances the dancer's
silhouette!
It emphasises your
'core muscles' and a session of Pilates can make you work up a
sweat! 
Yoga has a meditative quality to it and there are other aspects to
Yoga, like deep breathing, balancing, etc, that I found to be
really beneficial to one's overall health. Yoga's not just
posing... if done correctly, you can actually find yourself
sweating too! 
BTW, is exercising one of your new year resolutions, Honeybunz?
