Good sex depends on many different things, but one of the main ones is being able to let go and enjoy those moments.
In a moment of intimacy if a woman is thinking: "I wish we could turn the lights off so he doesn't see my cellulite" or "Man, I can't hold my stomach in for much longer," there is not a great chance that she will be reaching all the potential pleasure peaks.
There is even the distinct possibility that she will be wishing the experience away, hoping for the moment when she can take refuge from exposure in the comforting camouflage of her twenty- tog duvet.
Letting concerns about our appearance get in the way of something as intimate as sex seems counter intuitive and even vaguely ridiculous.
It seems all the more ridiculous because it is an insecurity felt most acutely by younger women, who generally don't realise just how lovely they are, and more importantly because during sex most men are not that conscious of body details.
They see cellulite, stretch marks, spare tyres, but they don't really care, it is, in truth, a very unusual man whose desire would be staunched by a dimple.
Between women, it seems that emotion is more important than appearance, and interestingly, recent research indicates that women are more likely to achieve orgasm with other women.
This is in part, one has to assume, down to insider knowledge of the equipment involved, but it also has to be down to comfort and trust. People less inclined to be stuck in their heads during sex are more inclined to achieve pleasure.
So, whilst letting concerns about our appearance get in the way of something as intimate as sex seems vaguely ridiculous, it is also rather sad and very revealing.
In one of the most remarkable statistics in the Herald Female Body Image Survey, 50pc of women say that they have "avoided intimacy due to feelings of insecurity about their bodies".
As might be expected it is slightly higher in the 18-24 age group (54pc) but it is quite something that half of all women have felt that their bodies are not good enough for sex at some point.
Fifty per-cent of women, presumably the 50pc who have not avoided intimacy because of how they feel about their bodies, think their appearance makes no difference to how their partners feel about them. Half of women are content with their bodies as sexual entities. Half are not.
Thirty four per-cent of women believe their partners would find them more attractive if they changed their body shape. 57pc of all women (67pc of 18-24 year olds) think their lives would change if they achieved their "ideal body shape" and of those 34pc think that it would affect their romantic and sexual relationships.
It is naïve to assume that sex is always this amazing melding of spirits we were sold back in the "wait until you're married" days.
Modern sex, both in and outside of long-term relationships is a far more complex engagement than the mere mechanics would suggest.
Not least because such large numbers of women feel their bodies are not fit for function.