There's a concept called Shōshin in Zen philosophy, seemingly related to this childlike joy and wonder; it talks of letting go of preconceptions and for people to become open and eager, as a beginner would be.

Becoming adults we tend to see things in a different light from children would; we would see things as how we think of them, with our past experiences, rather than for what they are.

So with shōshin, normal, usual, mundane things or events can even seem to be wonderful, new and interesting. It's not that difficult to change a little of one's mindset bit by bit, and things will start to change in a bigger scale.