Sexuality has become such a taboo topic in our society, yet it abounds everywhere. Somewhere, someone couldn't separate distrustful and negative sexuality to positive, healthful sexuality. Somewhere, people lumped all sexuality in with being a taboo topic, and now, it's considered disrespectful to even bring it up. This to me, is incredibly unhealthy. In my book "Fattitude: Lose your F in Attitude", I have an entire chapter on the importance of recognizing not only sexuality but in sexual health. For instance, in our society, the focus of impotence is on a mans sexual worth even in commercials for pills meant to boost his erection; however, impotence is scary stuff. In about 75% of the men who visit an emergency room suffering a cardiac episode, they had some form of impotence as a warning beforehand. Impotence is directly related to cardiac health. The focus should not be on men performing like trick ponies at a festival or circus, but on their spirit and health.

Yoga has been proven, medically, to help both mens and women's sexual health, from PMS to ovarian cysts, to impotence and prostate health. It helps breast health in both men and women and overall stimulating of lymph nodes to help full range immune function.

Not often discussed, is the more topical levels of sexuality that most people can relate to. Intimacy and sexual orgasm.

In yoga, the focus is on the self, not the external. In consenting, mature sex, there is often a focus on pleasing the other person and often for some, there is a shame in their body or performance. I can't tell you how many women have told me that they do not feel good about their bodies so, they prefer to be in the dark when in a sexual union and, they also are worried what their partner thinks of their body.
It's not just women. Men of all ages have body insecurities also, but they range more from a performance stance. 
In yoga, when we are on the mat, in the beginning it is easy to look around the room and compare yourself to others and feel yourself judge your own body, performance in yoga and abilities. However, it is learned through yoga that this is the opposite of inner peace, and as you learn to not look around and focus on others, you are forced to look within and accept who you are.
Yoga helps the physical aspect of yoga in this way also. Although pleasing your partner is certainly a union-based focus, it is not the main focus. The main focus of sexuality then, becomes being more at one with your partner and with full acceptance of how you look, feel and behave, you can be who you are fully, and relax through the union rather than worry. This alone increases your sexuality, and they are more attracted to you because of your own self love. 

Rolling on from this, we take it a level deeper into intimacy. In yoga this is important to have inner peace. When we have this inner peace, we are accepting more of ourselves as well as of others. We learn to cope differently and we literally change our chemical make up, increasing our ability to be more open and loving. We also are changing ourselves to love ourselves more; so negative behaviors from others or from ourselves are less tolerated; our relationships either become more healthy or, we make changes to leave unhealthy relationships. We grow and evolve; sexually this is huge. As we grow on the yoga mat, our relationships can't help but improve with others.

From a pure physical aspect, we increase tone in our body in ways that traditional "exercise" just can't do. We have not just postures but "postures within postures" with prompted physical locks and gazes to help us learn to control our bodies and release stress when we feel tightening of certain muscles. 
For instance, some women and men who have had sexual abuse or simply negative sexual encounters may feel lower back issues, incontinence, lack of orgasm regardless of how they "feel" about their partner, cramping, digestive issues in the lower intestine and more. When we learn that sometimes chronic bracing or tightening of certain muscles can constrict nerves, and that constriction long-term can cause failure to thrive of certain organ health and action, we are able to address this during yoga. Yoga has been proven to help people overcome not only emotional issues but some physical issues that they thought were "just them"... and address things on the mat that carry on the other 22-23 hours when you are not on the mat.

Let's also be realistic; a great body means not only that you can feel sexual but that you are able to accept sexuality easier as well. Increasing muscle tone and flexibility gives you a larger range of ability to enjoy sexual union, and the tone of your muscles helps you to increase your ability to orgasm more dynamically. 

Respect for sexuality, and respect for the human spirit are integral in true sexual health. Realizing that sex is not taboo, but a part of you to be trusted, not just tolerated or turned away, is so important to all parts of who you are. 
Yoga can help you to reach all depths of who you are, in a way that is pure and healthy.