Ninety Year Old Patient

A 90 year man finally gets to see a Dr. and the dr. asks him what the problem is, the man says he wants the Dr. to lower his sex drive. The Dr. is taken aback a bit but finally asks the man, just how old are you? The man answers I am 90. The Dr., still a little confused says you are 90, and you want your sex drive lowered? Yes said the man, it's all in my head and I want you to lower it.