From: 40 Things You Should Know About Sex By the Age of 40
18. If you're too tired, it's too bad for him.
"The best thing about getting older is that you can do—or not do—whatever you want. Say it nicely, and your partner should understand if you've got a headache or you want to watch the Desperate Housewives marathon instead of making love. Unless, of course, the marathon—or the headache—is a weekly event."