The late Billy Graham once wrote that 95% of Christians live spiritually-defeated lives. That means only 1 out of 20 Christians live the victorious Christian life. Why are so many blood-bought, born-again Christians being defeated? It is because they keep picking a fight with letting go of their own will. They refuse to surrender to the Holy Spirit.
When you read the famous but often hard-to-understand passage in Romans 7:13-24, it is easy to get the feeling that the fight against our flesh is futile. It would be had Paul ended his gospel to the Romans in such a manner. Thankfully, he did not.