How do we live the life we now live in the flesh day by day?
The life we now live in the flesh day by day is lived by the faithfulness of the Son of God, who loved us and gave Himself for us. It is not self-effort; Christ lives in us, and God keeps and empowers us to live a life pleasing to Him.
Les explains that the believer is crucified with Christ: when Christ died, that is when we died, yet we live physically—not by our own self, but Christ liveth in me. The life now lived in the flesh here and now, day by day, is lived by the faithfulness of the One who bought us. He is faithful and will never let us down. Paul goes on to say it is by the faith of the Son of God, who loved me and gave Himself for me. Les contrasts Peter's words in Acts 2, “you killed the Messiah,” with Paul's message, “He died for you.” God is able to keep us, empower us, and enable us to live a life that is pleasing, showing that He loved us and gave Himself for us; this we must constantly remember.
I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me.