Paul described his personal struggle with his two natures in Romans 7:1-25. He concluded by saying, "O wretched 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" (v. 24-25). John described the state of the believer as being one of righteousness, or being one of sin (unrighteousness - 1 Jn. 1:8-10). Notice his epistle was written to those who are said to be in a state of fellowship with other believers, and with God, Himself (1 Jn. 1:3).
James explained how a believer can guard himself against living according to his fleshly desires, and living according to the will of God. He wrote, "But be ye doers of the word, and not hearers only, deceiving your own selves. For if any be a hearer of the word, and not a doer, he is like unto a man beholding his natural face in a glass: for he beholdeth himself, and goeth his way, and straightway forgetteth what manner of man he was. But whoso looketh into the perfect law of liberty, and continueth therein, he being not a forgetful hearer, but a doer of the work, this man shall be blessed in his deed" (Jam. 1:22-25).
Believes are controlled by someone: the Holy Spirit, or themselves!