In this paper, we briefly review the cognitive and related literature to understand why the older we get, the more we perceive the speed of time to increase - there is a clinical reason for this nature-related aging phenomenon. We then show that nurture-related or experiential factors can also affect our perceived speed of time. More specifically, time series data that concern factors which impact our daily lives can be used to model our perception of time. It is shown that nurture reinforces and about doubles nature?s impact; that is, the older we get, the more we perceive time to be speeding up. Interestingly, when age is controlled, the experiential data suggests, for example, that a 62 year-old in 1997 perceived time to be about 7.69 times as fast as that perceived by a 62 year-old in 1897; this phenomenon is less extreme for younger aged persons. Finally, it should be noted that understanding the way we perceive the speed of time over time is not only an important endeavor in its own right, but it also has potentially significant impact on our ability to cope, on our work productivity, on our lifestyle, indeed on all aspects of our life.