An elderly gentleman named Sam wasn't feeling well and went to a
famous clinic for a complete physical. They checked him from the
roots of his hair to his toenails and, when they were finished, one of
the doctors visited his room to give him the results. 

The doctor began by saying, "Sam, we want you to know that for
someone your age, you're in amazingly good health. However, we
do feel it would be best if you would cut down on 50% of your sex
life." 

The old gentleman sat back and kind of smiled and said to the
doctor, "Well, doc, that's all right. But tell me, which 50%?? Thinkin'
about it or talkin' about it?"