The verb is passive, and that is not a grammatical detail. We are being transformed. Nobody in this sentence is transforming themselves.
What we are doing is looking. Unveiled faces, turned toward the glory of the Lord. The change happens to people who keep looking, and it happens at a speed they do not set.
The veil is not decoration. Paul has spent the chapter on Moses, who came down from the mountain with a shining face and covered it, so that Israel would not watch the glory fade. Paul contrasts that fading glory with a lasting one. Under the new covenant the covering comes off, and it comes off for every believer, not only for one man on a mountain.
That is a relief and an irritation at once. A relief, because the pressure to manufacture your own growth comes off. An irritation, because you cannot hurry it either.
With intensifying glory is the phrase for the pace. Degree by degree. It assumes a long time and a great many ordinary mornings where nothing measurable happens.
Think about the first minute of your day. The alarm goes off, and before your feet reach the floor you are holding the phone, reading headlines, checking who wrote overnight. Nobody decided that. It is simply where the face turns when nobody is steering it. Do that for a few years and it will shape you too, just as slowly and just as surely.
So the question is not how hard you are trying. It is what your face is turned toward, most days, by default.
Look at Him for ten minutes today without asking for anything. Before the phone, if you can manage it. Read a passage slowly and sit with it. That is not a small act. It is the whole mechanism.