Struggling with sin is not an obedience problem. It's a faith problem.
The answer is not trying harder to obey. That only works for a little while.
To live free from sin, we must continually stir up the faith that God has given us.
How do you stir up faith? You continually do three things with the Word of God:
Hearing. Remembering. Speaking.
Let's make it practical. The next time you are tempted to sin, head to Romans 6 and read verses 1 through 11.
Then, say this, "I consider myself dead to the power of sin and alive to God through Christ Jesus."
Every time you do this, faith is stirred. And faith in what God says is the only thing that will enable you to live free from sin.