I have to have discipline?

In our small group on Sunday nights,we're beginning a book by Foster entitled "Celebration of Discipline". It's about the spiritual disciplines.He categorizes them into inner,outer and corporate. I'm really excited about this as i've heard the word "spiritual disciplines" but not ever known what they were exactly.I already practice some of them but would have never considered others as disciplines.Also,tithing is not one mentioned and I just KNEW that was a discipline.So,i'm really excited about what i'm going to learn over the next few weeks.My question to you is this....Did you grow up knowing what spiritual disciplines were? What do you think they are? If you practice spiritual discipline,what's your favorite and what's your least favorite? which one has been most life changing? i'd love to hear your thoughts :)