Everything!! The treads - I am working at my own pace yet get given enough of a "push" from the instructors to keep adding and making myself better each class. I personally need that added "push" from the instructors. Rower is hard but satisfying once completed. The floor work is great - I used to hate weights and floor work. Now I am starting to really love it. And that's 100% because the instructors make it fun, which in turn makes me want to do it.