Notice Paul doesn't just say “stop being anxious” and leave it there. He replaces the command with an action: pray, petition, give thanks. Anxiety isn't dealt with by willing it away. It's dealt with by redirecting it toward God, specifically, with gratitude attached even before the outcome is known. And the peace that follows is explicitly described as something that “transcends understanding,” not the product of finally having your questions answered, but a peace that operates even when your circumstances remain confusing or unresolved. Then Paul does something practical and easy to overlook. He tells you what to think about instead: true, noble, right, pure, lovely, admirable things, because a mind can't simply stop thinking. It can only be redirected toward something else.