Romans 8:10: But If Christ Is In You, Although The Body Is Dead Because Of Sin, The Spirit Is Life Because Of Righteousness
 But if Christ is in you, although the body is dead because of sin, the Spirit is life because of righteousness. (ESV)
At first glance, it seems as if Paul is talking about physical death. He says, "although the body is dead." We need to understand the context of this verse to fully understand it. Paul has been talking in the previous verses of how it is our body that is prone to acts of death, i.e. sin. In our minds we want to do what is right, but our bodies are prone to sin.
At the end of chapter 7 Paul cries out, "Who will rescue me from this body of death?" Jesus Christ will rescue us! If Christ is in us, we are alive, but we have a continual struggle with the body of death. One of the differences between those who are Christians and those who are unbelievers is how they attempt to control their sinful body.
The unbeliever tries to control his body in his own strength. He does not have Christ dwelling within him. He is completely incapable of controlling sin. The Christian has the advantage. God's Spirit dwells within and now the very power of God is available in order to gain the victory over sin in the human body.
For the believer the focus should be on the Spirit of God. The Spirit is life. We are no longer to be led by our own bodies, but rather we are to bring our body into submission to the will of the Spirit of God who lives in us. Our body is dead because of sin, the Spirit is life! If you want to walk in victory you must walk in the life of the Spirit.
Your physical body is prone to sin. Sin leads to death. Look to the Lord for forgiveness of sin. He will fill you with his Spirit and you will have life. Be led by the Spirit, not by the flesh.