Multi-tasking is great for computers but not for humans!
Multi tasking creates inefficiencies, in that the lack of focus on the job in hand causes all the activities to be undertaken sub-optimally.
Certainly, one should have variety in one’s work or life but the activities should be dealt with sequentially.
As for keeping one’s brain in reasonable working order, Luminosity is one of the better ways, along with learning languages as Dr Alf has discovered for himself.
My approach is simpler and involves the ingestion of 44 vitamins and minerals daily, plus GH3 Advance, which in serum strength form slows down the effects of ageing quite markedly.
I continue to read extensively, undertake interim work, travel, exercise modestly, drink hardly any alcohol, fast 2 days a week, get an adequate amount of sleep, network with interesting people and avoid foods which cause memory loss, such as those containing glazed sugars, whilst eating foods which contain Lethicin, such as green vegetables which seems to help.
Testosterone supplements, reciting certain mantras practiced early in the day along with alpha brain wave entrainment and interacting with younger and more intelligent people than myself also assists the process of slowing down the inexorable march of time.
Periodically, changing one’s route to places and observing things aggressively, rather than being in a state of semi-trance helps and to remember more. I read late at night in a somnambulist state so that the material enters my subconscious as many Actors do to learn their lines.
The late Zig Ziglar, the American motivator, who started his life as a preacher used to counsel watching a lot less television and learning new things whilst driving or at home.
This process plus examining comparative religion /competing philosophies, mixing with people of different cultures, avoiding polluted environments and keeping up with new developments is what I have found helpful to maintaining balance, mental alertness and rationality in a world filled with seductive distractions, symbolism and easy answers which do not deliver.