Discipleship is conditioned upon our relationship to our Savior in three areas: His lordship, His leadership, and His love. His lordship renders us a subject in His Kingdom. His leadership renders us His servants, implying submission. His love is that which motivates us to surrender and serve Him as our King and Savior.
The Lordship of Christ is not the last chapter in the disciple's life. It is the first chapter. It is the beginning of the very life of the believer, because salvation is basically bowing to Him as the Sovereign Lord who saves. One does not "make Jesus Lord." One must bow to the Lord Jesus, whom God has already made Lord (Acts 2:36).
Discipleship is not an option for a true believer, and the Lordship of Christ is not an option for a disciple. It is part of his discipleship.