A decade ago, there was an interesting psychology study done at Stanford.
In the study, a young child was left alone in a room with a marshmallow. The child was told that they could eat the marshmallow whenever they wanted; however, if they waited until the research assistant returned before eating the marshmallow, they would be rewarded with a second marshmallow.
Results varied widely from child to child: some children couldn't help but eat the marshmallow immediately, others tried desperately to resist the marshmallow's lure by hiding it or closing their eyes, and still others simply waited patiently for the assistant to return with no signs of struggle whatsoever.
Years later, the researchers called to check in on the children, and found an exceedingly strong correlation between the children who easily resisted the marshmallow and those who were doing well in school. The children who immediately gave in and ate the marshmallow tended to be struggling with school and discipline issues.
Confronted by this evidence, the researchers formed two postulates. The first solidified years of conjecture that self-discipline is a huge determiner of success, both in young children, and later in adults. In fact, some researchers even went so far as to claim that the two biggest factors of a person's success in our culture were 1) the ability to resist impulses, and 2) natural talent. In that order.
Their second postulate? That marshmallows are the root of all evil.