I enjoy solving puzzles.  Sorting through my initial state of confusion, creating some sense of relationship among elements to form a pattern, and putting the correct patterns together gives me a certain sense of accomplishment.  This year I am using a calendar that has a daily IQ challenge.  Some are visual, some are word problems, some are numerical but all get my mental process flowing nicely.  I'm finding I need to put aside my first reaction and look at what might be the real question needing to be solved.  (Yes, some times I do need to cheat and look at the answer then figure out how they came up with it!)  This is going to be an enjoyable way to expand my mental horizon over the coming year.  Hopefully, after a full year of these exercises, my mental box will be more flexible.