One finds that, in grade school, from elementary all the way through high school, the general consensus is that people wish to be older. People do not want to be the youngest in a class, or to look the youngest in a class. Endeavors many people pursue include things like driving, drinking, fucking, or voting, and one finds that these things are generally reserved for those who have compiled a certain amount of days in which they have existed on this planet as a human.
After leave of school, it becomes equally clear that people often then wish to be younger. Most wish to look younger - to be carded when going drinking - or to feel young and full of energy like they did when they were a young adult. Endeavors many people pursue include things like driving, drinking, fucking, or voting, and all of these things are easier, relatively speaking, when one is younger.
It strikes the present author that humans, then, spend a non-negligible amount of time wishing they were any age but the one that they currently are; whether spending their youth wishing to be older, or their old age wishing to be younger. Draw any profound conclusions from that as you will; one may suggest that the author would write something here which ingratiates the reader to a "live in the moment" type existence, but considering said author also spends a non-negligible amount of time wishing to be younger, such conclusions from the author would be, at best, hypocritical.