The big difference is between the inner comfort zone i.e. how you feel about and relate to yourself, and the outer comfort zone. i.e. the rest of the world and all the people in it.
I studied hard and challenged my inner comfort zone all the time until I found the ultimate goal which is more or less complete inner peace. Once you have this there is no fear of the outer world and thus no comfort zones needed. The outer comfort zone was and is much easier to negotiate once you challenge the inner.
THE additional issue is the collusion of so called friends and family who would seek to keep you in their own comfort zone rather than see you changing and becoming all that you might be, but perhaps leaving them behind, so you have to put up with their resistance as well as your own.