Time feels both short and long, in the moment and in hindsight. It always seems short on one scale, and long in the other. Either the days fly by, or the months do.
Well-spent days are ephemeral, but stretch on endlessly in the rear-view mirror; wasted hours seem to drag on forever, but hardly make any memories.
This is because we don't understand the length of a span of time directly; we think of times as "short" or "long" based on what we perceive as happening in that time. The more events our brain knows about from a period of time, the longer it feels like it was.
When dopamine-pumping headlines bombard you online, the onslaught seems endless: your brain is busy reacting to tons of novel information, so time creeps by! But you won't remember most of what you see, because it's ephemeral garbage. So, when you look back later, there's only the blank space of an empty afternoon.
In contrast, when you focus deeply on one thing, it's all your brain grasps, and the time seems to vanish in a poof! But putting so much thought into something builds a strong memory, which might last for years. Months filled with productive days feel longer in your rear-view mirror than the ones you frittered away, because their memories are still around—while wasted time leaves no lasting impression.
It's a striking paradox: the shorter your days seem, the longer they'll last. What's the best way to have memories of years chock-full of rich, deep recollections? Do whatever makes the hours fly by.