A neighbor of mine, Myron, in his mid-50's, had a relatively minor
heart attack, and while he was in the hospital, he complained to his 
cardiologist that he thought that his sex life was over. The
cardiologist said, "Not true, Myron. Sex is wonderful exercise for your 
heart. After you get home, you should have sex 3 or 4 times a week. It'll
be the best thing you can do for your recovery."
So after his discharge (from the hospital), Myron tells his wife what
the doctor had said. His wife looked at him and told him, "That's 
wonderful, Myron! Sign me up for twice."