Most people go day-to-day without spending much if any time thinking about the aging process. It’s not exactly a fun topic to think about, but there are certain situations in life that put it front and center. For example, have you ever seen someone, perhaps a friend or family member, for the first time in over six months or so, and you are taken back by the fact that she looks noticeably older? The next thing that likely comes into your mind is that you, too, probably look somewhat older. Being polite, no one says anything. I've been in that sort of situation a number of times. My guess is you have too.
Each of us has a time-lapse type image of ourselves that’s embedded in our memory. Over the course of a year it moves along slowly because we see ourselves hundreds of times and therefore we have a lot of images to process. On top of that our focus is skewed toward recent images which are fresher in our memory. So when a year passes we usually aren't able to notice much of an outwardly change in ourselves, nor are others who see you often. Aging for many remains cloaked.
In contrast when we see others after many months or years it’s almost as if we see fast-moving time-lapse photography. The big middle portion of what would be a mental sequence of images is missing, and instead we see a limited number separated by sizable gaps in time. This brings about a jarring realization, the unpleasant fact that, for healthy people post-prime (unhealthy people can often improve), each passing day brings with it a slight physical deterioration, and a little bit of life.
I think that it’s important to think about daily aging, at least once in a while. It makes it easier to savor experiences. It can help with motivation and time management. Ultimately, it can help you put your life in perspective.