When you are having fun the time flies while having nothing to do feels like being stuck in an anomaly in space-time where time doesn't move at all. While there might be some physical possibilities for time to move on a different pace that however requires either some extremely massive object being nearby or moving at relativistic speeds. And I doubt no amount of fun can make you move that fast.
But while having fun might pass the time more quickly as it happens, looking pack to those moments compared to those boring times look like a lot more time. A day, week or month where nothing happens is just that: a single period of time in our memory where nothing happened. A day when you had many exiting things happening takes a lot more "time" to remember through.
Boring life might lead to a longer life subjectively and while living it it might feel even longer. But looking back it could be just a moment, decades passing at the blink of an eye. The time just gets used up and wasted without giving anything in return. You might as well make those moments count so you still have something from your investment left after all the years.