"The idea of God’s glory is often associated with the advent of Jesus. Isaiah promised that “the glory of the Lord shall be revealed” in the day of the Messiah. Angels chorused, “Glory to God in the highest,” at Christ’s birth. The literal meaning of the Hebrew word for glory is “weight” or “substance”. In the eyes of men this literal meaning frequently lent itself to the idea that a person possessing glory was laden (heavy) with the substances of this world. Thus, Jacob’s flock was his “glory” (Gen. 31:1). The Assyrian’s power was their “glory” (Isa. 8:7). Joseph’s high position was his “glory” (Gen. 45:13). But when the word was applied to God it was meant to bring out the weightiness of HIS ATTRIBUTES - His love, justice, righteousness, mercy, power - His CHARACTER. For all that God possesses is simply WHAT HE IS. His “glory” is not what He HAS, but what HE IS. When the glory of the Lord is revealed, the LORD HIMSELF is revealed in all His wonderful nature and character of being. Glory then is not something intangible, or ghostly, or transcendental. If it were this how could Paul ask men to reflect it? Stripped of its physical connotation it is BEAUTY, moral and spiritual beauty, beauty infinitely real, infinitely exalted, yet infinitely near and infinitely communicable."
Much more in the link:
https://www.kingdombiblestudies.org/antichrist/antichrist1.htm#7
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"Upon these astounding yet perfectly obvious psychological facts, Paul bases his statement of how men are changed into the image of Christ. “Make Christ your most constant companion” - this is what it practically means for all who treasure the hope of Sonship to God. Live out all your days in intimacy of fellowship and in vital union with HIM. Be more under His influence than under any other influence. Every character has an inward spring, let Christ be it. Every action has a key-note, let Christ set it. Begin every day with the mirror placed at the right angle, turn it towards HIM, and even to your enemy the fashion of your countenance will be changed. Cultivate His friendship. Live after Christ, in His Spirit and in His Word, as in His Presence, and it is difficult to think what more you can do."