I talk a lot about making sure you add variation to your workout to prevent your brain and your muscles from getting bored.
You may find that you love your current workout because you've finally mastered it and changing now seems like the worst idea ever. Maybe you love the girls in your Pilates class? Or maybe you've just mastered all the moves to your Step II class? Problem is that not changing things up reduces the physical benefit because your muscles adapt and don't work as hard, which may explain why you love it so much. Since most of us are more inclined to stick with a workout we love, trying something new and hating it could lead to the doom in our workout careers. However sticking with what we love is becoming more of a social pat on the back than working out. So what's a girl to do?
My suggestion is this: Still do what you love but also make it a point to try replacing your current workout with something new at least once a week. For example, if you're really into Vinyasa Yoga then stick with it, but add a cardio class this week too.
Who knows, you might find that you love something else just as much!