Muscles that aren't exercised regularly tend to become weak. Recent research indicates that brain cells are similar to muscles in this regard. Memory and brain fitness improve with stimulating brain exercises for all important areas of the brain. Crosswords alone are not enough because they don't exercise all parts of the brain. Brain exercise needs to include activities like drawing and learning a musical instrument.
My latest theme is unlearning. Unlearn bad habits, unlearn bad practices, unlearn irrelevant cultural riturals. Unlearn the crap.
Our minds are so full of irrelevant learning so often that it is difficult to experience and live in the present. The joie de vivre comes from letting go of the trash thoughts and the trash learning.
Engage without the baggage and live forth with renewed energy.