One can wake up in the morning and chant the mantra “Aham Brahmasmi” – “I am Brahman” and whether they believe it or not does not matter a whit. It is true whether they believe it or not. So really this mantra, like many others, is a bit of a daily affirmation. Just like many forms of prayer. “God protect me”, “God be with me” are all just things one says to reinforce the idea that God is with them, that they are protected. It helps to strengthen one’s resolve in carrying out his daily dharma. And it really doesn’t matter whether he believes it to be true or not. It is already done because he is Brahman.
Jai Hari Aum.