There is a famous study in which researchers left kids alone with a marshmallow.
If the kids waited to eat their marshmallow until the researcher came back, they would get a second one.
Some kids ate the first marshmallow right away. Others waited a minute or two. A few made it to the end. Researchers watched these kids for years and found that the longer the kids had waited, the greater their future “success” (defined as behavior, SAT scores, professional achievement and so on).
I never took this test, but I can imagine what might have happened if I had…