Tat Wong Rocks.
It took me a while to finally join, but once I did I realized it was probably the smartest thing I've done my self in years. It's not mundane and redundant like all the other gyms and healh clubs in SF. The classes are incredible--what a work out!, the teachers and very knowlegable, and it's made me look forward to going to the gym everyday. Didn't think that was possible.
They might be a bit more expensive than a gym membership but totally worth it. No nagging, great payment plans, extremely flexible schedules, excellent teachers. I could go on. I will recommend this to all my friends