You might be surprised to know that it's an ancient technique, thousands of years old. Maybe not by the common people, but ancient priests and sorcerers, meditators and spiritualists.
Energy balance.
Saving and spending energy wisely.
Saving energy is interesting. It's a matter of going deep into pleasurable energy (not necessarily intensifying it but memorizing it), so it can be called upon in more difficult times.
So it's a combination of spending the energy wisely, as you say, not splurging on less important trivials, so that when more common energy comes it looks better, and then memorizing the good when it happens, to reuse it when things are down.
The memorizng focuses on the energy not the event, this way it's more easily used to enhance different (less pleasant) events.