I'm going to argue two seemingly contradictory points. First, a point about systems optimization.
You don't optimize a system by optimizing any one part of it. To optimize a system, you have to sub-optimize its parts. Let me illustrate what I mean by talking about a life.
Your life is a product of so many things: your physical health and fitness, your mental health and learning, your social life and psychological well being, your sense of meaning, your connection to the community around you and your sense of individuality in the community around you, your sense of legacy, individuality, belonging, your income and financial security, your cool shoes or cool car or cool taste in music, your hedonistic pleasures of food and sex, the hunger for stories that comes in the consumption of books and movies, or your tribal urges that find expression by cheering for your team and so many other things.
Here is the deal, though. If you optimize any one of those, you will sub-optimize your whole life. Do everything you can to be in peak physical condition and you'll likely have little energy left for something like plowing through great literature or keeping current on important new books. And if you do both of those things while working a full-time job, working out and reading all the great books, your social life will suffer. Life is zero-sum and if you optimize to any one piece of the myriad pieces that make up a life, you will sub-optimize the whole of your life. Oddly, the way to optimize any system - including and perhaps especially your life - is to sub-optimize every piece of it.
The punchline is perhaps cliche: a balanced life means moderation in all things.
Now the contradictory point.
This week there was some furor over Elon Musk's claim that to accomplish anything a person needs to work 80 hours a week. People pointed out that an 80 hour week is counterproductive. I totally agree. Long term. Short term? I think he's right.
A moderate, balanced life is not something that one achieves in any given instant. You don't split up each hour into 7 minutes for workout, 3 minutes for reading great literature, 8 minutes for building relationships, 4 minutes for eating, etc. Even within the course of a day or week we focus on just one thing at a time. So in any given instant, we're certainly not balanced.
There are times in life when you need to move forward. In those instances you look for the limit or obstacle to moving forward and you challenge that. You do optimize to the part that is the limit .... at least until it no longer is.
So then the question is, if you are going to optimize a life but not any one part of it, what does it actually mean to sub-optimize in a way that is best for your life? It means that you have stretches of life that really do optimize for one part of it and subordinate everything else. Let's say that you have children. You don't want the entire rest of your life dedicated to doing what is best for your children, optimizing everything for them. But in those first few months? First few years? Maybe even first decade or so? You will optimize for them. Nobody with a newborn is running marathons or throwing big parties or reading great literature. They're sub-optimizing pretty much everything to that one thing: the newborn.
If you create a dissertation or book or symphony or business, pursue a gold medal or partnership in a prestigious law firm, you will probably go through something similar to what one goes through with a newborn. You're going to sub-optimize to that one thing. At least for a few years. New parents are not going to say that they'll only put in 40 hours each to care for their newborn; it would die in the other 88 hours of the week. A similar, but less dramatic thing, can happen with any of these ventures. Balance suggests that you never dive into anything: success suggests that you do.
And maybe you just keeping diving into things for the whole of your life. Or more realistically, at various times in your life that could be separated by six months to six years of "la de dah," days in which not a great deal happens. (That perfect storm of incredible opportunity for which you are incredibly well suited at the right time of life only happens one, two, maybe three or four times a life.) You throw yourself into things that result in sub-optimization elsewhere. You're immoderately out of balance at every stage and the end result is a full life that is balanced in that it lets you experience life as whole over the course of a whole life, but never in any one instant. Because in the end, a life takes a lifetime and if you're interested in a legacy of any kind, you don't even optimize for a window that small. (But that's the stuff of another post.)