"Those who are in the flesh can not please God. But you, you are not in the flesh, but in the Spirit." Romans 8. 8, 9
This verse highlights the problem of any tempted believer in his life. It is clearer in other translations that use the phrase "in the grip of the flesh" instead of "in the flesh".
In the verse of the day, the flesh designates this human nature imbued with sin since the fall. It leads us to sin, it can not please God.
On the other hand, the Spirit of which we are sealed is that divine person who lives in us. We discover with him our relationship of child to Father: he "testifies with our spirit that we are children of God" (Rom 8:17). In him we walk in a way that honors God. He lives in us from the "new birth", according to Jesus' teaching to Nicodemus : "That which is born of the flesh is flesh; and what is born of the Spirit is spirit. Do not be surprised at what I said to you: you must be born again" (John 3: 6).
The mysterious change that this spiritual experience produces in us can be compared to the liberation of a slave who discovers freedom. At first, he struggles to live as a free man, as the weight of his past has conditioned him to feel like a slave, to think and act like a slave. It is the same for the child of God: although freed from sin, he still acts often with this flesh marked by sin. This is what the apostle Paul says : "I take pleasure in the law of God according to the inner man; but I see in my members another law ... which makes me captive to the law of sin" (Rom 7. 22, 23). We must accept and live the truth day after day : "I no longer live, but Christ lives in me" (Gal 2: 20).
Let's not be discouraged by our inevitable falls in our earthly life. Let's rely on God's forgiveness to lift us up and help us walk in this world to his glory.
Source (To please the Lord)