About This Answer
To counter sexual desire, Ajahn Dtun points to contemplation of the body. One trains to see one's own body and the bodies of others as asubha, seeing their decline and impermanence. When the mind sees the impermanence of form, it lets go of its delight in that form; otherwise the mind proliferates around what it sees and feeling and desire follow.
He offers a way of looking in three layers: see the form in front of you, then see ageing overlaid on it, then see death. This needs samādhi and wisdom, so he suggests beginning with what is easy to see from outside, such as hair, nails, teeth and skin.
He then gives a simple exercise. If someone's eyes seem beautiful, imagine the eyes removed and ask whether the form is still beautiful. If the nose seems beautiful, imagine it gone, leaving only the bony cavity; imagine the teeth taken out. Practised like this, the mind sees the impermanence of form and lets go.