Spiritual discipline as Willard defines it is "activity carried on to prepare us indirectly for some activity other than itself." In other words we don't do Bible reading just to read the Bible better, but to live the Bible better. The practice of righteous living helps prepare us to live righteously. Indirect discipline is often a bridge to get us to the next season or to bring us to the answers we're seeking. When I look back on my life, I can identify seasons when God had me practice disciplines that made no sense, but later on I realized how he was preparing me for the season to come. I'm so grateful for the leading of the Holy Spirit. A disciple lives by an active obedience kind of faith that follows Christ without needing to have all the answers.
I encounter many Christians who have difficulty overcoming the simplest things and give in to the urge to say an unkind word, or act self righteously, or insist on being heard instead of hearing. To me this means they missed the practice the Lord offered them in their personal times with him. If I can learn to listen to the Lord in prayer instead of talking the whole time, I may develop the discipline to listen to others. Practice makes us aware, alert, and observant to the opportunities all around us to live righteously. We miss these opportunities because we've not practiced the indirect disciplines.