There may be disagreement about whether or not telling teenagers to not have sex works but that could be due to puberty. In younger kids, cookie abstinence works just fine. Even the Cookie Monster can get kids to eat fewer cookies, and cookies are kind of his thing.
Deborah Linebarger, an associate professor in Teacher and Learning at the University of Iowa, studied a group of preschoolers who repeatedly watched videos of Cookie Monster practicing ways to control his desire to eat a bowl of chocolate chip cookies.
"Me want it," Cookie Monster sings in a video, "but me wait."