I just found this great quote from Henri Nouwen in Bread for the Journey: A Daybook of Wisdom and Faith. I think that it is the best definition of discipline that I have ever heard. Rather than emphasizing the rigors of repetitive action that many of us struggle with it focuses on the result – time & space for God
Discipline in the spiritual life is the concentrated effort to create the space and time where God can become our master and where we can respond to God’s guidance. Thus, discipline is the creation of boundaries that keep time and space open for God – a time and place where God’s gracious presence can be acknowledged and responded to.