Two gentle suggestions...
To the "Use it or loose it, a mind question" people -- improve your grey matter by looking up the difference between "loose" and "lose."
To the "Use it or loose it, a body question" people -- please don't do the latter anywhere around ME!
Ok, that was snarky of me. The fates will probably punish me by putting a typo in here somewhere for everyone else to point out.
Seriously... I'm learning ceramics on the wheel, slowly
studying Italian, working the NY Times Crossword and other puzzles, and improving my three-dimensional problem-solving skills by putting in a kitchen. I don't detect much of a difference in brainpower, but maybe that's the point.
I was thinking that taking up the guitar might be a good idea too, since I have never tried my hand at a musical instrument before.
Or maybe I'll join Audreyh1 in birding -- that's interesting stuff. (I once spent half a day watching a water ouzel dive for food in the Grand Canyon -- what a dynamite little bird!)