The Stanford Marshmallow Study: into which category do you fall and have you seen this play out in other people's lives?

The children who were willing to delay gratification and waited to receive the second marshmallow ended up having higher SAT scores, lower levels of substance abuse, lower likelihood of obesity, better responses to stress, better social skills as reported by their parents, and generally better scores in a range of other life measures.

The researchers followed each child for more than 40 years and over and over again, the group who waited patiently for the second marshmallow succeed in whatever capacity they were measuring. In other words, this series of experiments proved that the ability to delay gratification was critical for success in life.
http://jamesclear.com/delayed-gratification