2 Corinthians 3:18 "But we all, with unveiled face, beholding as in a mirror the glory of the Lord, are being transformed into the same image from glory to glory, just as by the Spirit of the Lord." (NKJV)

Now with our face uncovered (Moses wore a veil over his face when he came down from Mt. Sinai with the Ten Commandments, because God's Glory reflected off his face and shone so bright the the Israelites were afraid to look upon it. Exodus 34: 28-29), as if looking in a mirror, we reflect the Glory of God. And as the Holy Spirit works Within us, we become more and more like Him and reflect His Glory even more!
Simply put; the more we grow in the Lord, the more we glow like the Lord!