Now seems like a fine time to read this Scientific American article titled The Art of Lying by Theodor Schaarschmidt. According to a study conducted by UC Santa Barbara psychologist Bella M. DePaulo and referenced in the article, people make up around two stories every day. Apparently, children "initially have difficulty formulating believable lies, but proficiency improves with age. Young adults between 18 and 29 do it best. After about the age of 45, we begin to lose this ability." From Scientific American:
Current thinking about the psychological processes involved in deception holds that people typically tell the truth more easily than they tell a lie and that lying requires far more cognitive resources. First, we must become aware of the truth; then we have to invent a plausible scenario that is consistent and does not contradict the observable facts. At the same time, we must suppress the truth so that we do not spill the beans—that is, we must engage in response inhibition. What is more, we must be able to assess accurately the reactions of the listener so that, if necessary, we can deftly produce adaptations to our original story line. And there is the ethical dimension, whereby we have to make a conscious decision to transgress a social norm. All this deciding and self-control implies that lying is managed by the prefrontal cortex—the region at the front of the brain responsible for executive control, which includes such processes as planning and regulating emotions and behavior.
"The Art of Lying" (Scientific American)