Working on puzzles helps our minds to stay young, aside from just being enjoyable. Some folks do crossword puzzles daily. I prefer math puzzles. And yes, I do them daily.
I started years ago doing Sudoku, which I thought originated in Japan, but after some research (of course) it also has roots in France and puzzles by Howard Garns in America. But we know it as Sudoku, which is the registered trademark in Japan. Sudoku is a logic based combinatorial number-placement puzzle.
So Ken-Ken takes Sudoku a step further by including math operations. (This one is also my personal favorite, at the moment.)
Then there is Kakuro, also from Japan. Again from Wikipedia: is a kind of logic puzzle that is often referred to as a mathematical transliteration of the crossword. The objective of the puzzle is to insert a digit from 1 to 9 inclusive into each white cell such that the sum of the numbers in each entry matches the clue associated with it and that no digit is duplicated in any entry. It is that lack of duplication that makes creating Kakuro puzzles with unique solutions possible, and which means solving a Kakuro puzzle involves investigating combinations more, compared to Sudoku in which the focus is on permutations.
Of course there's always just the basic logic problems to solve.
No judgment, please. This is just how my mind works. Doing these puzzles is my way to relax while getting my mind in gear. And yes, I actually really enjoy them!!