On a tangent, the ability to delay reward is largely determined by the time you are 5ish years old, but unlike height and IQ, people don't think of it that way.

On a tangent, the ability to delay reward is largely determined by the time you are 5ish years old, but unlike height and IQ, people don't think of it that way. See the Marshmallow experiment, which has been succesfully replicated a few times. It is a big reason why life is unfair.