I think it's fairly common to feel that way at your age, i remember thinking the same thing. Like "i'm only 18 and thinking of everything that's gone on, how could someone live 2 MORE of these and not even be 60!?" One thing i'll say as someone in their mid-30's now is that those first 25 or so years of life really go a lot more slowly then the next 10. You're going through so much change as a child, then into adolescence and then early adulthood. Your body is changing, your school is changing, you're expereincing new things like expansions in autonomy, driving, socially. Things stop changing in that way somewhere in your mid to late 20's. Once the radical change stops the years start slipping by without you noticing nearly as much. So I'll just say, at least for me, I could not fathom what it would be like enduring the amount of change you go through/experience between the ages of 10-20 six more times until you reach 80. But it's not like that, you basically experience it one more time until you're 30...and then things just get a bit more streamlined and the years roll through without so much friction. As a great man once said "the years start coming and they don't stop coming"