"Who shall save me from the wretched body of sin? " Paul asked when he battled with the thong in his flesh, the agent of satan that afflicted him.
He wants to do God's will in his mind, but in his body of sin, he does what he hates or does not want to do. In his mind, he wants to obey God, but in his body, he does what he hates. Sin has used the law, which is perfect, to arouse what is sinful in his body.
In this state, Paul asked who could save him from the sinful nature that wanted him to do the opposite of God's command. He realized he could not save himself with his efforts or righteousness because he failed in his attempts to obey God's righteous commands.
He is like a man who has reached the end of himself and admits his helplessness in fulfilling the perfect commandments of God. He fell on his knees, prayed to God about his sinful nature, and asked how he could be saved from his body of sin.
The answer came in the form of Paul declaring that he thanked God for our lord Jesus Christ who provided the answer to his question.
Christ provided the solution to humanity's problem of sinfulness by dying on the cross. We are saved by God's grace and unfailing love towards us despite our sinful selves and rebellious, disobedient nature, which war against the spirit of holiness.
"For it is by grace you have been saved, through faith—and this is not from yourselves, it is the gift of God— not by works, so that no one can boast." Epesian 2 8-9