No believer is immune to the activity of the flesh. The flesh with sin is very much present as long as a person is alive. Therefore, the need to exercise the spirit all the time. No genuine spiritual man will easily deal with the flesh, for the more mature a person is, the more he recognizes how sinful he is. The teaching of sinless perfection is just an utopian dream.
No believer can boast ever that he has overcome the flesh all forever. If any claims such, he must be ignorant or blind or at the best a novice. The more one grows in the Lord, the more conscious he becomes of his old man, and thereby, the more he look to the Lord for His blood washing, cleansing and covering. The flesh is very alive but he can be limited, restricted and subdued by our willing cooperation with the Spirit to deny the flesh. This is the exercise needed of every believer. And this is to work out our daily salvation day by day.
The Lord even exposes me these days of how old I have been, and how sinful I have been. The flesh, given opportunity is just the incarnation of Satan manifesting his notoriety. No wonder, the Lord rebuked Peter and said, "Get behind me Satan!", even after the glorious revelation of Christ and the Church. Often when not in the spirit, the soul coils down to the bosom of the flesh fully entwined with, in all his heinous deeds. However, if such happens there is a way out! Halleluijah!
The precious blood of the Lord Jesus Christ is so efficacious! Whenever I fall or sense a guilt within, I come boldly to the throne of grace, apply the blood, offer Christ as my trespass and sin offering and claim the victory of Christ. With this experience bit by bit, day by day, I am climbing the highway of Zion step by step. The enemy may do whatever he may, the Lord is and ever be my Shepherd leading me on and on. The old man will be alive until my last breath, but I must exercise my spirit and starve him to naught.
"Lord preserve me day by day and grant me the grace I need to be in You and one with You all the time. Save me from my self, my old man and my flesh. Lord, keep me in You, in my spirit all day long, all the days of my life."