Play at a thing that makes you uptight: experiment with the opposite way of doing something that frightens you. Take a different route to work. Let a kid boss you around (really do what they say – wholeheartedly). Waste time. Don't shower. (Well, maybe just shower at a different time of day; I dunno: maybe skip a day.)
See the movie, Big, and take it seriously; I mean, really BE a kid; no one has to know. Choose bewilderment.