Words are only representative of thoughts and therefore vibrations. The universe does not respond to words... only vibration. This is why for example we can say anything we want to try to cover the truth and the universe will respond to the guilt we feel instead. Or why we can use affirmations over and over that don't feel true to us (we're speaking the words) but the manifestation stays the same, because even though we say something like "I love myself" our vibration and thoughts say "no I'm worthless". The reason to pay attention to our words is that they are indicative of the vibration we are giving off.