Want to eat that marshmallow right now? You can, but here’s the catch: if you wait a few minutes, you can have two marshmallows.

(Argh!)

Turns out that kids who can wait — who can control their impulses — grow up to get better grades, and score 210 points higher on the S.A.T., on average. The marshmallow study, originally performed by Dr. Walter Mischel, is one of many showing that self control–the ability to ignore tempting distractions and keep one’s emotions in check–stands at the root of achievements of all kinds.

So is self-control innate? Or can it be taught, developed, and practiced? For the latest answer, check out Paul Tough’s fascinating story about Tools of the Mind, a promising new program that teaches self-control through — surprise! — play. Turns out that dramatic play helps kids develop and improve their ability to keep impulses in check. As Angela Duckworth puts it, “Just because something is effortful and difficult and involves some amount of constraint doesn’t mean it can’t be fun.”

As much fun as eating two marshmallows, you might say.

PS — Thought-provoking discussion on this from Po Bronson and Ashley Merryman over at the excellent NurtureShock.