Heh, I'm 40 and the secret is that the most erotic part of the body is your mind. Communication is the key. No, a 40 year old body does not walk around in a constant state of horniness like a 20 year old. Try 20 years of that and it gets a little old and you learn there is a lot more to it if sex is to be anything more than using your partner as a masturbation tool.
Ladies, it's in the mind. Talk about it. Two heads. Got to give attention to both. (sorry if that is a bit vulgur).