All Christians struggle with sin.
Many times even relatively mature Christians commit sins they thought they had long since left behind and end up struggling anew with sinful habits in thought, word, or deed. Naturally, this means they must rouse themselves to action in putting to death the deeds of the flesh.
Such action requires motivation. The hope of the gospel–the promise that if we suffer with Christ we will also be glorified with him (Romans 8.17)–will be an all-important factor in helping such saints press on and bear their cross as they pursue that holiness without which no one will see the Lord (Hebrews 12.14; c.f. the Westminster Confession of Faith, XIII, Paragraph 1). The promise of continual and repetitive forgiveness will be another such factor (First John 1.9; Matthew 18.21-35), needed for us to confidently begin again after having constantly fallen short of the glory of God and his great grace to us. Finally, we will need also a confidence in the power of God to change our hearts and minds and attitudes and actions.
While there is no magic bullet for this struggle, I have found something that one can do in this midst of this war that might be of help to some. What has helped me is found in First Corinthians 12.3:
I make known to you, that no one speaking by the Spirit of God says, “Jesus is accursed”; and no one can say, “Jesus is Lord,” except by the Holy Spirit.
This might help in any number of situations: