I sometimes feel like sex is just another chore. So...when I'm not in the mood and DH is, I tell him that if he wants sex, he's going to have to make it some damn good sex or I won't like it. He goes all-out---gives me as many Os as I want, rubs my back, tries different positions, etc. I suppose this probably qualifies as a form of blackmail, but hey, he does not mind because I also reciprocate with a pretty decent blowjob to warm him up and he gets what he wants. So...maybe that's why I don't really feel too guilty about that.