Definitions
From a Christian Perspective

Discipline: Training to obey God’s rules and to act in accordance with His will. The training part is made up of teaching, exercises (testing, trials, etc.), and a regulated and repeated set of activities (regimen) which develops and improves our yieldedness, faithfulness, and skill at obeying God’s rules and living according to His will.
Self-discipline:
1. First, it is training yourself through learning, exercises, and a personal regimen – with the goal of overcoming your weaknesses in order to improve your obedience to the rule of God and your submission to the will of God.
2. Second, it is using your training to control your thoughts, feelings, choices, and behavior in the daily affairs of life so that you live according to the will and word of God.

God’s Discipline: God’s direct and specific activity in our lives of teaching, training, and correcting for the purpose of improving the consistency of obedience to His word and submission to His will so that we are more willing and better equipped to live by faith.