Like Apple Arcade, Fitness+ suffers from trying to appeal to everyone and thereby appealing to no one. It leans heavily towards entry level calisthenics, with gratingly cheerful instructors and cross promotion of annoying Apple Music pop songs. The forced banter and lame jokes between the instructors is particularly annoying.
The clear opportunity is to offer highly personalized and progressive workout programs in different sports (weight training, yoga, cycling, etc) that use Apple Watch and Health data to help you progress. No more pre recorded video knock offs of what was popular on Peloton in 2020. People want real coaching and guidance to reach fitness goals, not phony motivation from plastic instructors. By all means, offer a beginner track for encouraging Joe Q Public to get off his butt and do some jumping jacks, but that can’t be the entire service if they hope to maintain interest and attract enthusiasts.