Reminds me of the Stanford marshmallow experiment. Researchers offered children one marshmallow, but if they didn't eat it, they promised a second marshmallow later. The children who had the "willpower" to wait for the second marshmallow did better in life on many measures.<p>An attempt to replicate this study found that childhood economic background was the best predictor of both willingness to wait for the second marshmallow and later life success. It wasn't "willpower" per se - it was that some of those children had grown up believing, from experience, that a second marshmallow is never promised and you're better off eating the first marshmallow now.