The thing that changed this for me is, no joke, having kids. This brought me away from the feeling that life is fleeting with little point to the minuscule things I may accomplish and showed me a grander scale. As an engineer, I'll never be a Maxwell, Shannon, etc., but I can raise the generation to come in a way that - though I may never know it - could have an incredible influence on the world.
btw, I know the other commenters mean well with sharing their experiences, but to be blunt, folks should not be having kids because there's something missing.
Of course, with everyone else having GPS and the Internet, it becomes much harder to find somewhere to sleep, because the amazing places you may have discovered fifty years ago will now be fully-booked months in advance.
The truth is that a dream isn't meant to be reached or achieved, it's meant to inspire people to do more than just sit around under trees smoking pot all day. It's a nice lie they tell themselves as to why they're trading time with their families for time at the office.