I was about to start posting with the title:  How Many Strings Does a Zither Have ?  Classic Arts Showcase on TV in the morning sometimes influences me on what to write.  The first video had Anton Karas playing the zither for The Third Man , and I noticed there were a whole lot of strings.  I have problems with just four of them on my ( wife's ) ukulele.  The zither had to be a greater challenge. But my first duty of this day was to exercise my knees, so I switched the station to the '70's.  I do this on Tuesday, Thursday and Saturday mornings before breakfast.  It's been just about a year now, and as might be expected, but nevertheless to my astonishment, my knees are not a problem now when I walk on a golf course.  But more than that: My posture is a lot better when walking. My toes are stronger in the bathtub when taking a shower.  I didn't realize before how important they were in maintaining stability. I've gained a quarter inch in height, a combination of