Verse: There is therefore now no condemnation to them which (who live in union) are in Christ Jesus, who walk not after the flesh, but after the Spirit. Romans 8:2
So often after people get saved they feel as though they come up short. Living a life free from sin is impossible. Only one man ever did it and that was Jesus Christ. But there is good news.
We who have accepted Jesus as our Lord and Savior and live in union with him are no longer condemned. Because in our mind we choose to serve God we are set free from the law of sin and death. Trying to live without sin is overwhelming.
We are made of flesh and spirit. There is a war going on between our flesh and spirit. We overcome the urge to sin by bringing our mind back to Christ, praying, studying the Bible, meditating on a verse, listening to Christian music, etc. But sometimes that is not enough.
At times we will sin. It is important to not dwell on the sin. If you dwell on your mistake it will weaken your spirit. Instead dwell on the fact that the law of the Spirit of life in Christ Jesus has made you free from the law of sin and death.
One of Jesus Christ disciples and one of the best apostles who ever lived explained the war between the flesh and the spirit as follows:
For we know that the law is spiritual: but I am carnal, sold under sin. For that which I do I allow not: for what I would, that do I not; but what I hate, that do I. If then I do that which I would not, I consent (agree) unto the law that it is good. Now then it is no (not really me) more I that do it, but sin that dwelleth (lives) in me. For I know that in me (that is, in my flesh,) dwelleth no good thing: for to will is present with me; but how to perform that which is good I find not. For the good that I would I do not: but the evil which I would not, that I do. Now if I do that I would not, it is no more I that do it, but sin that dwelleth in me. I find then a law, that, when I would do good, evil is present with me. For I delight in the law of God after the inward man: But I see another law in my members, warring against the law of my mind, and bringing me into captivity to the law of sin which is in my members. O wretched (miserable) man that I am! who shall deliver me from the body of this death? I thank God through Jesus Christ our Lord. So then with the mind I myself serve the law of God; but with the flesh the law of sin. There is therefore now no condemnation to them which (who live in union) are in Christ Jesus, who walk not after the flesh, but after the Spirit. For the law of the Spirit of life in Christ Jesus hath made me free from the law of sin and death. For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh: That the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit. For they that are after the flesh do mind the things of the flesh; but they that are after the Spirit the things of the Spirit. For to be carnally minded is death; but to be spiritually minded is life and peace. Because the carnal mind is enmity (opposed) against God: for it is not subject to the law of God, neither indeed can be. So then they that are in the flesh cannot please God. But ye (you) are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his. And if Christ be in you, the body is dead because of sin; but the Spirit is life because of righteousness. Romans 7:14 - Romans 8:10