In American culture, unless you're financially constrained, you grow up with someone hammering down the idea that you have to be doing something productive and getting better 100% of the time. If you're a kid, you have to be involved in clubs or teams for everything. You have to make friends. You have to be good, you have to be popular. You have to get awards. You have to play a couple of sports competitively. On holidays, you have to go to summer camp, shock full of controlled activities. You have to do a lot of "voluntary" work because it will look good in your resume, not because it's helping someone [1].
As a result, your schedule is controlled, you are being judged 100% of the time, and the loudest, more outwardly energetic people are the ones who strive. The idea is that if you're not having Mandatory Fun, you're doing something wrong.
It creates this idealistic culture where everyone is trying to be better all the time, or pretending they are. The reality is that most people live in a constant state of anxiety. For the most part, it's very hard for kids to find what they like, and get better at it by sheer initiative; they never have time to do it. Instead, they do what they do because they're told to.
Little surprise kids have no time for introspection, and that's the way people can actually get better.
Science is just starting to understand that Rest is not Idleness [2]. The idea is not new [3]. But our culture, specially the fast-moving tech culture, is not ready for it.
[1] http://www.huffingtonpost.com/2011/12/05/college-admissions-...