Affirmations are spoken at the surface of the mind. The pattern they are trying to overwrite lives several levels below, and it was not installed with words. It was installed with experience and emotion.
This is why repeating a sentence you do not believe often produces the opposite effect: each repetition quietly reminds the subconscious of the gap between the statement and the self-image.
Change that lasts speaks the language the pattern was written in. That is what subconscious work is for.