Desire arises in the mind and if you hold on to the desire it becomes an obsession. One of the fascinating things about human birth is our intellect is developed vis-a-vis animals. This allows us to make decisions & analyze. Depending on what tendency is strong in you, the mind can be pulled in that way. People who discipline themselves in their life tend to be very rigid and subdue those desires that are against their core beliefs. This leads to frustration within that festers, and usually comes out as anger or lust. When the gust of wind comes the trees that survive are the ones that are flexible to allow the wind to pass through. Thus in life be flexible to desires, if they come observe and let them pass.
As humans the desire for sex in rooted in our very psyche. This is because one of our survival needs is procreation, and sex is the method to pass bodily fluids for that purpose. Craving for sex all the time leaves the mind dull and lethargic, subduing the desire for sex leads to frustration. But simply understanding that this is a need, allows us to deal with this better.
The concept of energy centers in the body is well explained and therefore it is important to understand that when different desires come, different energy centers become active. These can be simply understood by observing the sensation in the body when a desire arises. Better understanding the body-breath and mind relationship helps us to respect the laws of nature and have a peaceful co-existence.