By the way, the marshmallow study has been redone and reinterpreted. It has been found that the children's behavior is heavily influenced by their life experience. When they live in an environment where they can't trust adults they eat the marshmallow sooner, quite rationally. So it isn't an inherent trait of the child but of its environment whether it waits for the promised future return or not.
I've seen an interview with a researcher who said something along the lines of "we take reliability into account" - but what he then said seems to show a very narrow interpretation. The experimenter must be well-known to the children and has played with them before the experiment, and that "the marshmallows are right there in front of them, so it's not a reliability issue". Personally, I don't think that is even remotely enough to account for the effect and that is a somewhat naive take on the issue, especially the second part that solely relies on reason. Which doesn't even work in adult scientists to counter social effects.
Run an n=1 study on yourself. Even if it's full of placebo effects and doesn't generalize to anyone else, as long as you figured out what makes you feel/do better, you win.