Our flesh has a bent toward wickedness thus our natural tendency is to do evil. Many people do not recognize this tendency and think they are "good", but we all go against the established laws that God has set up for our protection.
Disciplining yourself to avoid wickedness is a sacrifice your flesh will have to make. We cannot expect to indulge in the pleasures of this world and receive intimate fellowship with a holy God.
We must learn to discipline ourselves in every area of our lives. The act of making a life-long sacrifice must be a discipline that comes out of a heart of love. If we are following Jesus Christ, we are his disciples and are learning His disciplines.
When we discipline ourselves we are training ourselves to do things that do not come natural for a wicked man (person without Jesus Christ) to do. The disciplines of Jesus Christ are living a life of sacrifice to Him, and godliness which can then be broken down into smaller areas.
Godliness will uphold a life of purity, mercy, and faith that is stretched yet firm in the Lord, etc.... To be honest, discipline and sacrifice go hand in hand and cannot really be separated.
It takes real discipline to offer yourself as a living sacrifice to God.