Why Do We Lies?

i really do try to not lie. And i think about why, and i think there re at least two reasons. It just feels like a small, but significant emotional trama every time you tell a lie. The other part is that it becomes costly to lie, in that you have to keep track of your lies, or otherwise you'll be caught. Then the cover up is worse than the crime. This gets me back to the question of why we lie.