Discipline is part of our lives whether we want to admit it or not. Anything we have done in life that has been important or long-lasting has some aspect of discipline involved; in practice, preparing, or doing. Sports, hobbies, academics, relationships, etc. all take some aspect of discipline.
Lack of discipline in certain areas often leads to failure or inadequate results.
What about our Christian lives? Do we apply discipline to our spiritual walk? Do we daily seek Him out in prayer and Scripture? Do we allow the Holy Spirit to sanctify us and make us godlier through His Word?
Here is a great book that points out the Scriptural foundations for having a disciplined walk with Christ.
Spiritual Disciplines for the Christian Life by Donald S. Whitney
Scripture Reading & Study, Prayer, Worship, Scripture Meditation, Evangelism, Serving, Stewardship of Time and Money, Scripture Application, Fasting, Silence & Solitude, Journaling, Learning
1 Timothy 4:16 "Pay close attention to yourself and to your teaching; persevere in these things, for as you do this you will ensure salvation both for yourself and for those who hear you."