Music: as in a gift certificate for music lessons. That’s the answer to the question posed in the title. Music calms, motivates, and engages. Students who play music score better on standardized tests, do better in math, and have a better chance at earning more money as adults. Troubled students taking music lessons of some sort also have been shown to improve attendance and increase their cooperation with teachers and other students. That’s not to say those things will guarantee a happy life, but they usually help get you there.