When you form words together in a particular order and put them out there, it is a conscious, deliberate, voluntary act. Things like body temperature, rate of breathing, heart rate, blinking -- those are all involuntary actions. So when you put ideas together and speak them, you know what you are doing. I suggest that you wait ten seconds before speaking so you can change a lie to the truth or say nothing. This speech habit will make you enemies as well as making your life quite miserable.