What a great post @wiseagent friend..!
I particularly think that the brain must feed itself every day, the mechanized routines in our homes and workplaces do not help much because they are learned routines and thus have been fixed in our memory, however the best "mental exercise" I find in reading , in learning a new language and in mathematical exercises, always things that force thinking and stimulate mental agility and one of the added values is that somehow this acquired knowledge remains as gain.