" So we introduced a token system.9 The children were given ten tokens at the beginning of the week. These could each be traded in for either thirty minutes of screen time or fifty cents at the end of the week, adding up to $5 or five hours of screen time a week. If a child read a book for thirty minutes, he or she would earn an additional token, which could also be traded in for screen time or for money. The results were incredible: overnight, "

― Greg McKeown , Essentialism: The Disciplined Pursuit of Less