Since I was one of those who lived at sea level and was kicked by 6,000 feet, I know how the low end of the bell curve feels. There is a distribution curve of people and how much altitude will affect you.
So a couple of observations/notes:
1) Getting exhausted is a really bad idea and one of the major things that gets altitude sickness going.
But altitude sickness has to do with oxygen partial pressure in your blood AND water retention in your cells "edema".
2) A low salt low sugar diet and drinking tea to keep the water from flowing into your cells will make you feel a lot better.
3) staying well hydrated gives your body lots of fluids to flush things out with.

I took diamox for years for altitude, it basically acted as a mil spec diuretic and I'd pee about 3/4 gallon after taking it. I would get "lung edema" where the cells in my lungs would swell up and start to hurt. I'd take two diamox tabs and in half an hour I felt better and could breath better.
WARNING if you do carry or borrow Diamox - if you take any aspirin containing drug, it could be your last. Never carry aspirin and diamox in the same first aid kit.

I'm camped over ten thousand a few times, once right after coming up from sea level. It wasn't fun.

It takes about two weeks to actually acclimate to a new altitude as it takes that long to produce the red blood cells required. All you can do is climb slowly, play high and camp low. A 1,500 foot drop in altitude is all that's required to "rescue" someone suffering from AMS. Acute mountain syndrome. What I'm saying is that you sleep maybe 1,500 feet lower than you hike or play at. The beying higher during activity seems to make sleeping 1,500 feet lower easier. And the one thousand feet per day sleeping altitude increase after to you to the "point" which is different for everyone.

Like if you go up to 8,000 feet the first night, then over a pass at 10,000, then sleep at 9,000 the next night, but of course, thats in an ideal world.

I found that once acclimated, if I spent a few days every other week at altitude, that I didn't suffer. Now I live at 4,000 and going to 9,000 feet I feel no pains.

AND, your brain does shrink a bit as you get older and if you notice that you don't get headaches at altitude after age 50, thats why - your brain has more room to expand inside your skull.

Jim YMMV I think diamox is acetaminophen