There was a test done back in the 1970s at Stanford University.
LINKThe test involved four year olds.
The kids were given psychological exams and physical exams, logic tests, and IQ tests.
It did not matter how the kids scored on IQ or any other test on how their lives were later rated for success.
The success in life for the kids could be predicted best by the "marshmallow test".
They would take the kid and have him sit in a room with a plate with a marshmallow on it.
The child was told he/she could eat the marshmallow if they wanted too...
... or if they waited they could have 2 marshmallows (a reward).
The child waited with the marshmallow for 15 minutes.
A minority of the kids had the self-discipline not to eat the treat. These kids were later found to have the highest SAT scores, GPA and the healthiest later in life regardless of IQ or other measurements.
One of the most important traits you can try to instill in your children is self-discipline.
I learned of this from a book I am listening to called "The Power of Habit". A good read.