My brain thinks it perfectly reasonable to do things such as go for long walks, climb stairs, sit in one position operating a keyboard and staring at a monitor for hours, eat great slabs of pie, drink multiple bottles of beer, and all sorts of other things, without having a bunch of lesser body parts get all whiny and complain about how they're being abused. Not that the brain is doing so well, itself. It forgets a lot of things now, and then gets pissed off when the nose tells it that something is burning or the taste buds tell it that it left out an important ingredient. When confronted with its failure, it usually blames some unnamed blood vessel for bursting or constricting or something.
The brain is turning into a curmudgeon. Or maybe it was a curmudgeon all along, but always directed its curmudgeonly attitudes out toward the world, and I never noticed them until it decided to start criticizing me. Well, parts of me, at least. Right now, for example, my back is telling me to go do something else for a while, and my brain is all pissy because it wants to keep writing. The back is about two minutes from getting its way. As I said, aging is all very good in theory. You gain knowledge and experience and wisdom and all that, but you have to cut back on the ice cream. It's an unfair trade. The brain has finally gathered enough information to know what it wants, and now it has more to do, and then various body parts start falling apart, and you don't even get to eat half a cake as compensation, because your stupid kidneys would shut down. Aging bites.