Wikipedia link of the day:
According to a 1985 study, this phrase is “the most effective subliminal message to aid in self motivation”. Evidently it triggers feelings of comfort to enable people to get over their anxieties and, I don’t know, quit smoking and such.
Something about the whole thing makes me a little bit suspicious, like the fact that this whole conjecture is based on a single 20-year-old study that, as far as I know, has never been duplicated. Still, if it’s true, it might have practical uses. If you could sneak the phrase into a sales pitch, you might see a significant sales uptick. And of course if you could somehow make that the name of your product, it would be like a license to print money.