If you're a certain age, you remember doing endless leg lifts in your best Jane Fonda costume to terrible 80s pop music. Fast forward a bit, and it's sweaty spinning classes that attract the masses. Whatever the year, there has always been one hot workout trend that everyone is offering and everyone is doing -- whether they really like it or not. Now all that has changed. The hot trend for today is...whatever you want it to be. At long last, fitness clubs have started to recognize that we're all different, ...