Having kids showed me how to convert a continuous quantity, time, into discrete quantities. You only get 52 weekends with your 2 year old. If Christmas-as-magic lasts from say ages 3 to 10, you only get to watch your child experience it 8 times.
If life is short, we should expect its shortness to take us by surprise. And that is just what tends to happen. You take things for granted, and then they’re gone. You think you can always write that book, or climb that mountain, or whatever, and then you realize the window has closed. The saddest windows close when other people die. Their lives are short too.
One heuristic for distinguishing stuff that matters is to ask yourself whether you’ll care about it in the future. Fake stuff that matters usually has a sharp peak of seeming to matter. That’s how it tricks you. The area under the curve is small, but its shape jabs into your consciousness like a pin.
Cultivate a habit of impatience about the things you most want to do. Don’t wait before climbing that mountain or writing that book or visiting your mother. You don’t need to be constantly reminding yourself why you shouldn’t wait. Just don’t wait.
Source: Life is Short, by Paul Graham