When you are young time drags, it seems forever until your birthday, Christmas, the school holidays. Seconds seem like minutes, minutes like hours, and days are an eternity.
We are told that our perception of time differs because of the number of "first-time events" at different stages in our lives. When we are young everything is new, we experience things for the first time and make stronger memories. Because things are new we look forward to them more, focus on them, and the resultant longing makes everything between seem slower.
As we age we have less first-time events, we fall into routines dictated by the requirements of our adult lives. We go through the motions longing for the time to go home, or the weekend, we wish our lives away to escape the monotony only to find that we have nothing to show for the time that has gone. It catches up with us, escapes us, passes us by.
We are told that we must continue to seek out new and unique experiences, not to go to the same old places and do the same things. We should be making distinct memories so that the days and months are not a blur of sameness.
We should plan ahead, have more things to look forward to, to long for, so the intervening time appears as it did in our youth. The more valuable (at least physiologically) the event, the more we long for it, the slower the time passes. This is why individual days seem to last forever but the weeks disappear almost without us noticing.
We long for the wrong things.
But, maybe, time is a function of our mortality. When we are young we have all the time in the world; 30 or even 20 seems old, a lifetime away, our future is infinite and we cannot grasp concepts such as forever. As we age we become ever more aware that our future is decidedly finite, limited, and our longing turns to fear.
That which we long for is elusive, just beyond our grasp, yet that which we fear rushes to greet us, eager to make its presence felt.
So we must not fear the passage of time (although that is sometimes easier said than done) and ensure we are longing for the right things, that we actually have the right things to long for, force ourselves to seek out the new, the challenging, the exciting.
Only then can we embrace life, truly live it and keep our mortality at bay.