I suffer from fear of death.

When I started college 4 years seemed like an impossibly long time. But it was over quickly.

The same thing happened with the decades of my life passing. Now it doesn't seem hard to imagine another 2 decades passing which will put me in my 70s.

Another aspect is seeing many relatives grow old and die, including my parents.

I am having more health problems as I get older.

A few months ago I came up with the profound thought that every old person I see in wheelchair or with a walker was once my age.

Not believing in an afterlife doesn't make things any better.

I try not to think of all this, because when I do it is existentially depressing.

At one time 20 years seemed like an impossibly long time. But I have lived through more than two 20 year periods, I realize how quickly it can pass. And that scares me when I think about it.