Paul is stating the results of his faith/union with Christ. Because he has put all his confidence in the work of Jesus, because he has been united with Jesus through faith, the death of Jesus was also considered to be the death of Paul (see Galatians 2:20). It is as if Paul himself was crucified on the cross (Galatians 5:24; Romans 6:1–14). The result of this union is new life in the Spirit (Galatians 3:2–4; Galatians 4:6; Galatians 5:13–25). The desires of Paul have been changed and are continually being changed. No longer is he focused on pursuing and giving himself to that which the world esteems (for example, the works of the flesh, Galatians 5:17, Galatians 5:19–21). Rather, he is now pursuing the fruit of the Spirit (Galatians 5:22–23).
14 But far be it from me to boast except in the cross of our Lord Jesus Christ, by which the world has been crucified to me, and I to the world.