If you want to keep your brain cells active, try some of the following exercises: read the newspaper upside down, do cross-word puzzles, try writing poems (if you are not good at that, do it anyway just for yourself, until you think it is good enough to share with others), buy a descant recorder and the instruction book and learn to play it. It is easy to learn music this way and it stimulates the brain! Put a book to the mirror and try to read the text that you see in the mirror and finally make a list of ten items and try to memorize them, then see if you can remember them. Write them down and check them against your list to see how you went.