Of our three limited resources – time, energy and money – time is the most rare and irreplaceable. Energy is the least rare of the three. It can be manufactured through coffee or excitement, and it can be predictably earned back through regular sleeping habits. Humans seem to possess reserves of energy as well, and when we "pull an all-nighter" we are dipping into that reserve. Energy debt has less of an effect on us than financial debt. The goal with energy is to simply have enough for each day, and most of us have more than we need.
Money is more rare than energy. It can be earned back in a number of ways if it's lost or spent; you can raise your rates, get a new job or even win the lottery. The goal with money is always to just make sure you get the most value for each penny you spend.
Time, though, is the most rare of all. We cannot manufacture it ourselves, and it cannot be borrowed from others. What we have is a steady, dependable stream of limited time. There are no reserves. We have 24 hours each day, and that's it. The goal with time it to get as much accomplished within each moment. The more accomplishment we can squeeze from an hour, the more we get done.
Our resources should be spent sparingly, thoughtfully and economically. I we don't do that, we're wasting them.