The troubles that you waste nights worrying about are rarely the troubles that actually strike. This sticks in my memory from a Chicago Tribune column by Mary Schmich , offering advice to the class of 1997 -- one year before my own high school graduation. It became a spoken-word hit when Australian movie producer Baz Luhrmann inexplicably hired an actor to read it against some jaunty ambient music, and the single was released to radio in 1999. A bizarre pop-culture moment that landed in my quote book , it often pops into my head.  Specifically the line, "The real troubles in your life are apt to be things that never crossed your worried mind, the kind that blindside you at 4 p.m. on some idle Tuesday." It was probably closer to 10 a.m. for me, but the Tuesday part was correct. On a recent Tuesday this month, I was standing in a mammography room with my left breast painfully trapped between two plastic plates while an x-ray machine moved in an arc in front of my face. This was