In the late 1960's, a psychologist named Walter Mischel conducted an experiment on a group of four-year olds. He gave each child a marsmallow and told them that if they don't eat it and wait for him to return in the room after 20 minutes, he would give them another one as a reward for being patient. Some children ate the marsmallow right away while a number of them were able to resist the temptation and waited.
Fourteen years later, Mischel followed up on the children. Those who couldn't wait suffered from low self-esteem and was regarded by their teachers and parents as stubborn, prone to envy and easily frustrated. Meanwhile, those who did not eat their marsmallows were more self-motivated, educationally successful and emotionally intelligent.
This study proved that people who believe in delayed gratification for better returns lead more positive lives.