I listened to a NPR story two weeks ago titled "Why Does Time Fly By As You Get Older?" The main theory discussed centered on how we encode our memories. The theory is that new experiences, generally from early in life, get encoded in memory with significant detail and as we get older our experiences can be more and more generalized based on prior experiences, a kind of memory shorthand. But the implication is that on recall a memory from early in life seems to have taken much longer that one from later in life simply because of the sheer amount of detail.
Commuting to work today I got thinking about this again because I realized nearly everyone was zoned out listening to their iPhones/iPods and the only thing that would have broken them out of the trance would have been something disruptive. On the program Neuroscientist David Eagleman explained, "when you drive to your new workplace for the first time and it seems to take a really long time to get there. But when you drive back and forth to your work every day after that, it takes no time at all, because you're not really writing it down anymore. There's nothing novel about it." As you do repetitive things you mind gets better and better at filtering out input that is non-significant.
Personally, observing myself growing older I have interpreted this change in how I experience day to day activities as a loss of the sense of awe that I had as a child. As such I have repeatedly made New Year’s resolutions that were less about change and more of a commitment to seeing common experiences with fresh eyes in addition to a continued openness to new experiences.
I feel it's one of our life challenges to keep an open and curious mind. To quote Socrates, “The unexamined life is not worth living.”