Ever notice how when you're on vacation, you start counting how many days you have left, and by Wednesday you're a little depressed that half of your week is over, and by Thursday a real pall has settled over you?
Of course, it's an incredible waste of your vacation to spend half of it depressed because it's coming to an end.
Life itself is not dissimilar. One thing everybody of my approximate vintage (1954) seems to agree on is that not a half hour of the day goes by where the thought of our age doesn't pass through our minds in some form or fashion.
If I could get someone to hypnotize me and make me believe I was 32, I'd be happy. I might die in 10 years, but it'd be okay: at least I wouldn't have wasted the final 10 years of my life being depressed that it was nearing its end.
And that really is a wasted life. But somehow, it also seems to be human nature to feel that way.