Are you trying to ‘crucify’ your old self — your “flesh” — and failing miserably? Stop trying and instead apply the truth, which is that as a believer, you ARE crucified with Christ (Galatians 2:20). You are because you were. You cannot crucify your flesh, your old self, but by knowing that you are crucified with Christ, through identification with his death on your behalf, the power of the “old man” — the “body of sin”– is destroyed in real time (Romans 6:6). Which is how Paul could write: “I am crucified with Christ” because he identified himself with the Lord in his death on the Cross.
“Knowing this, that our old man (former self) is crucified with him, that the body of sin might be destroyed, that from now on we should not serve sin. For he that is dead is freed from sin” (Romans 6:6-7) The life that we now live we live by the faith of — faith from — the Son of God, who loved us and gave himself for us. We “reckon” ourselves as being dead to sin and alive unto God through Jesus Christ. Water baptism is a ‘burial’ — the “old self” is not just dead but dead and buried!
Your crucifixion with Christ is a fact, and the application of that fact to your life is an ongoing, daily process. Just as in Law there is “guilt by association”, in Grace there is forgiveness by association with the shed blood of Jesus on your behalf and his “finished” work on the Cross. (“It is finished” were his last words as he died.
As the old hymn puts it: “Mercy there was great, and grace was free; pardon there was multiplied to me; there, my guilty soul found liberty — at Calvary.” Thank you, Jesus! The old “I” is dead and was buried in baptism.
The paradox is that: “The life that I now live in the flesh, I live by the faith of the Son of God, who loved me and gave himself for me.” The old “I” (NT Greek: “ego”) no longer exists in God’s eyes, only the new “I”, which lives by the faith of Jesus. Can you identify with this? It is Grace by association!