I discovered Joyce Rupp some years ago. She is an experienced spiritual director and retreat leader who has an extraordinay gift for expressing the princples of these disciplines in words on the printed page and, as such, is also a prolific writer. Here is something she said in an interview that I like:
To me, the spiritual life involves the whole of our life, every single part - no piece can be left out. I used to think of most of my life as one part and my spiritual or prayer life as another. In fact, I used to think that the rest of my life took me away from my prayer life. But now I see that nothing can be left out of a healthy spirituality. Another piece is that it's always about relationship with the divine, but also with other people. So it isn't just a God-and-me kind of thing. True spirituality will always take me out of myself, and I do believe that authentic spiritual growth has to take me out into the world. It can't just be a feel-good pacifier. The spiritual life is a call to be in transformation, to become our true selves. That means it has to have an openness to growth and change. The word spirituality sounds like something static rather than dynamic. I like the term spiritual growth because it implies that we're always in process. We can never say, "OK, I'm saved. I've made it. This is it. I don't need to do anything else. I don't have to listen to what's calling me to greater growth or greater spiritual depth."