Why isn't it the "right" way to do exercise? I do something similar with my "zone 2" cycling workouts, where I throw a movie on Netflix while I mindlessly pedal

Why isn't it the "right" way to do exercise? I do something similar with my "zone 2" cycling workouts, where I throw a movie on Netflix while I mindlessly pedal at a fixed power output. It's a great way to get in some exercise, especially in the Winter months when it's hard/unappealing to get outside.