What you think about during sex matters.
A guy who doesn’t want to, ahem, proceed too quickly will think of baseball or something non-sex related. A girl who wants to proceed more quickly might focus on surrounding milieu of a loving environment. These are stereotypes, I know, but the fact that we have them does confirm that what we think about during sex matters: what we attend to changes the nature of the experience.
In this vein, Mind Hacks links to a great review of the role of attention in sex. Vaughan makes the point that we tend to view sexual dysfunction as a problem of equipment — hence prescribing Viagra, when a more accurate diagnosis may be a problem of state-of-mind. Definitely read the whole thing.
It reminds me a funny sketch by one of my favorite comics, Dylan Moran (below the fold):