to their benefit

You assert this as if it were an axiom. It doesn't look like one to me. Show me the benefit.

And I still don't understand why would I want to become an ideal utility maximizer.

This is summed up by the question: "if you're so smart, why aren't you rich?"

For many LWers, the answer is "I'm young," but I think there are also a lot of people where the answer is "I am rich."

Given how you were talking about pains, it seems to be a noticeable issue for you

Yes -- it happens a few times a week, depending on circumstances.

Your advice would totally make sense if the baseline issue were that I'm not consuming enough water. But on a baseline day I consume between 1 and 1.5 gallons of water alone, not counting any water in the food I eat, or any other beverages such as almond milk. (I don't consume sodas, fruit juice, coffee, tea, alcohol, or really anything else.)

The problem is that sometimes, that 1-1.5 gallons isn't enough, and there are occasionally days where it's been not enough for a few days in a row, such that I end up running "a few quarts low". (I actually use my scale as another clue: if I've lost a pound or two from one day to the next, and my fat % is higher, then I know I'm dehydrating. But an hour or so difference in time spent sleeping can do the same thing to my weight, so it's not a very precise measurement.)

I don't know, sip 50ml every half an hour or something?

What makes you think I'm not doing that now? As pointed out elsewhere in this thread, my rate of water need is not constant. If I have a couple of days in a row where I underestimate how much I need to raise my intake to compensate for losses like having more conversations or physical exertion than usual (or the air conditioner running more to maintain the temperature inside!), then I will fall behind and experience dehydration symptoms. But if I try to consume more water as a matter of course, then that also disrupts my digestion, makes me feel cold, keeps me running to the bathroom, and so forth.

So, if you don't have some method for actually changing my body's regulation of water, I'm not interested. AFAICT I'm already doing everything that is doable with respect to changing my behavior around water consumption, given the lack of any reliable means for determining my precise water need, in a situation where both under- and over-consumption create health problems.

I'm going to tap out of this discussion now, as my original post was not a request for advice; it was an expression of curiosity about someone saying they experienced headache relief from both placebos and painkillers, making me wonder if it was water-related (since I have some experience of that).

I've been through the free will sequences a second time now, and I'm trying to figure out how to apply it to my life.

See, even that sounds weird, because applying to my life...trying...figure out...whether I do or not is inevitable, right?

Speaking from the naive standpoint, how does the determinist viewpoint affect your decisions? How do you think about it, incorporate it? Do you compartmentalize and pretend you're in control, or what?

What is best in life?

I'm not going to the gym because of the tragedy of the commons? I really don't think that's it.

The first question was why isn't everyone trying to change the world, with the underlying assumption that everyone should be.

Not everyone cares that much about "the world", and that's likely a good thing.

I would generalize the question, because the generalization applies broadly - whatever we profess to value, whatever we believe we value, why aren't we expending more time and energy actually creating that value?

One answer that pops to mind runs against encouraging people to "save the world" - that caring about things beyond your control largely only prevents you from caring about, and thereby having the motivation to act, on things in your control.

The "programmed" bit is where I see a problem. It's humans' ability to think and reason outside the replicator-level lizard brain urges that makes immortality problematic. We are able to recognize the fight to live, live to fight cycle of life.

I don't think life in general is that different from any specific "good" thing—given enough time, the novelty will wear off.

The option of immortality seems okay. Though it seems a bit arbitrary whether someone lives to 80 or 800 or 80 million. The more life = more utilons math never makes sense to me.

I've always thought it was interesting to think what you would actually do with eternity... You could have kids...like 1,000 kids. And fall in love every week. And win Nobel Prizes in everything. And travel to the edge of the Universe. Or create your own Universe and be the God of it. Etc. Etc. There might be thousands of years of novelty in that. Maybe millions. But the returns are diminishing. Just think of all the amazing stuff we completely ignore and are bored with already.

An example where it does not: a high-roller in a Vegas casino orders half a dozen hookers to his room.

How many of the people who engage in that behavior do you think would like it if it would be public knowledge? In many cases I don't think that those high-rollers want publicity for the action which suggests that their general status doesn't benefit from it.

I would probably say that some very old people are ready to die. I wouldn't call it "wanting to die", it's not an active desire, but I also wouldn't call it "apathetic" because it's more than just not caring.