After High School, I worked in a factory. The job consisted of sweeping, and working along the tail end of the production line. My job was to wait for the stacker to fill up with wallboard, wait for the guy in the forklift to pick up the contents, and then press the button, so the stack would rise again, to receive more wallboard.
My job consisted of pushing a button. In 8 to 12 hour shifts. Pushing the button did not require copious amounts of thought.
Now that I'm in programming, we are basically paid to think. About business rules, about coding, about processes, meeting deadlines, providing value and service.
Speaking of thinking, how many concurrent thought patterns can you keep simultaneously in your head. For example, let's say your spouse asks you to go to the grocery store. Says, pick up some bread. But if the bread from the bakery isn't fresh, then get a loaf from the aisle. But try to get whole wheat, unless honey wheat is on sale, then get two, otherwise only get one loaf.
And while you're there, get soda. But only get Coke, if they have diet caffeine free. If the bottles of diet Pepsi are on sale, get 2, otherwise get three diet coke 12 packs in the cans. If they have coupons up front, then get 4 12 packs.
Also, if they're out of chips, then drive to the store on Main Street, and if they have buy one get one free, then get 4 bags, otherwise just get 2.
And so on, and so on.
It's not necessarily the total number of items to remember in the head, it's the business rules surrounding those items and what if scenarios that go multiple levels deep and fragment off into new hierarchy's of logic.
I find that many people do not care to think much at all, let alone high processing thought power for 8 to 12 hours per day. Perhaps a route canal would be better or getting audited or spending time with the parents in law might be more pleasant.
Anyway, I don't claim to be exceptional at remembering complex logic patterns concurrent in the brain, but often times it is required to dig through mounds of logic, perhaps in an Excel file from hell, to track down all the twists and turns. Perhaps the best approach is to write down the logic, and make changes are necessary.
I find that this type of thought pattern can really wear you down quick and put you in a bad mood. But when you solve the riddle, it's all worth it.
And there you have it.