My father, the doctor, used to marvel at his use of time as the years went by. When he was a young, newly-fledged practitioner, he said he spent huge amounts of time and attention on each case. As his experience broadened - deepened - he didn't have to. That is, he could distinguish between urgent and not-so. He knew the difference and his skill developed so that he could deal with a dislocated shoulder in a matter of minutes and spend more time on something more complicated and serious. That's the principle of triage.
Remember that sort of a joke: a patient complains to a doctor about the cost of the treatment he has received, saying that the time it took couldn't possibly cost so much (like re-locating a shoulder?). The doctor explained the breakdown of the account: Pushing a dislocated shoulder back into place - $5.00. Knowing where to push - $100.00 (or whatever the going rate was).
I thought of that as I ponder my past. I had so much energy and I squandered it lavishly. I am more careful now and try to expend it where it counts, before I run out. I guess I needed to learn where to push.