That's the blessing and curse of having a body. It enables you to do all the beautiful and crazy things that come with being a human, but it requires consistent daily maintenance - at least an hour of exercise, 8 hours of sleep, and whatever time it takes you to source, prep, and eat healthy food.

Supplements can supplement but not replace this. My money is on boring supplements being the only ones worth taking. Magnesium (not magnesium oxide, most other forms are good), omega 3 with a good ratio of DHA to EPA, and creatine for enhanced energy (but probably no direct memory effects). Maybe B vitamins.

Get blood work done, see if you're deficient in anything and supplement or adjust diet as needed.

Beyond these basics, everything else is basically snake oil or has such tiny effects you won't notice anything.

And no supplements can do anything to make up for deficiencies in diet, sleep, and exercise, and this becomes more and more true the older you get.

Yes