Perceptions of Time
Our perception of time and relation to it radically shifts over the course of our lives. Our perception of the flow of time accelerates as we age, for example.
It's not until around age 35 that we get the ability to intellectually and emotionally relate to the future story arc of our lives. That's when we start being able to realize that not only have we changed in the past, we will continue to change in the future. This has profound consequences for our lives, including helping to drive the onset of the midlife crisis.
Also, our perception of events is heavily dependent on whether or not they are within our living memory. Any event within our living memory seems like it happened just yesterday, while any that happened before that seems like the distant past.