I agree that it isn't mandatory, @hardikv. But for a lot of people, I do understand that it gives their fitness attempts some structure. I know that a lot of people (beginners, especially) don't really know what to do on their own, be it home workouts, or even just what activities would help their goals. I'm personally a big fan of home workouts, even though I do participate in group classes (not gyms). That said, different strokes for different folks, eh? :)