As believers, beholding the glory of Christ in the glass of the gospel, we are changed into the same image and likeness by the Spirit of the Lord. So those beholding the beauty of the world and the things that are in it through the cursed glass of self-love are in their minds changed into its image. But we have not so learned Christ Jesus.
– John Owen The Glory of Christ
Reflecting on the glory of the gospel of Christ will change us. The Spirit will reprove, correct, and instruct through the Word, and we will be brought from faith unto faith as we grow in holiness. We are not merely getting better at being ourselves. Rather, we are becoming more like Christ. We are becoming Christ-like.
On the other hand, basking in the pseudo-glory of the world through our own selfish lusts will sink us into deeper depravity as we spiral downward. It may be subtle but the smaller changes are no less real. We will think the way the world thinks. We will be more concerned with self instead of others, never mind God.
The Christian that is reflecting on the glories of this world and not the resplendent glory of Christ has no hope for sanctification.