I've been reading recently in a couple of threads here as well as a few other articles, about the importance of staying mentally sharp as we age for both health and emotional well-being. I think a lot of us probably fulfilled the need for mental stimulation while w*rking. But for those who have retired, are there things you do to help stay mentally challenged? Reading fiction, reading non-fiction, taking classes, participating in local politics? Other things that you do that have the added side-benefit of providing some mental challenge?