Previously I wrote about desire from the viewpoint of personal experience.  Here I attempt a more detailed explanation of how and why I train to let go desire…
From a Buddhist’s point of view, something may be considered good or evil according to its impact on one’s state of mind.  A desire is neither good nor bad, it’s just a temporary mental phenomena. Attachment to desire – i.e. grasping at it as ‘good’ or ‘bad’ gives rise to intention, which leads to action (kamma) that may be skilful (i.e. results in a wholesome mind state for the doer) or unskilful (i.e. results in an unwholesome mind state for the doer). Our habitual failure to recognise this fact is the ‘ignorance’ that Buddha’s teaching of the Four Noble Truths was intended to dispel.
It will be obvious to anyone who meditates that the desire to harm another will result in an unwholesome state of mind (e.g. guilt, fear of retribution… etc.). And the desire to do good for another (e.g. by giving) will result in a wholesome state of mind unburdened by attachments. However, the Buddha taught that in both cases the kammic ‘fruits’ arising from such desire will eventually be exhausted and the doer will experience yet another round of samsara with all its problems. The ultimate aim for a practitioner of (Theravada) Buddhism, therefore, is to end the suffering of endless rebirths by walking the Noble Eightfold Path – what Bhikkhu Yuttadhammo describes as a ‘razor edge’ between liking (desire) and disliking (aversion). 
Initially I was drawn to Buddhism because I realised I was unsatisfied with always feeling unsatisfied, and Buddha’s Four Nobel Truth’s teaching had a ring of truth about it. There was strong desire to find peace of mind and freedom from discontentment, and it drove me to study and practice. Mindfulness practice is now a daily habit – just like brushing my teeth – and I do it mainly because not being aware of body, speech and mind is both dysfunctional and stressful. But the ultimate goal of enlightenment is not something that I spend much time thinking about, however; I just try to remain present and aware of how things are rather than dwelling on how I’d like them to be.
My daily practice is based very much on my reading of Ven. Ajahn Sumedho’s interpretation of the Dhammacakkappavattana Sutta.  He identifies three kinds of desire (tanha) –
- Desire for sense pleasure, or kama tanha. (When we’re hungry, for example, we can see that one mouthful of tasty food immediately results in desire for another. That’s kama tanha.)
- Desire to become, or bhava tanha. (We want to become enlightened like Buddha, for example. That’s bhava tanha.)
- Desire to get rid of, or vibhava tanha. (We want to get rid of anxiety, jealousy and anger, for example. That’s vibhava tanha.)
But as he also says, these three categories “are merely convenient ways of contemplating desire. They are not totally separate forms of desire but different aspects of it.” 
Through contemplating kama tanha, bhava tanha and vibhava tana I am learning that desire arises spontaneously and doesn’t actually cause suffering; the real cause of suffering is grasping at desire. How does one grasp at desire? By thinking, for example; “I’m hungry and I want to eat now!” Or, “I’m suffering through ignorance – I need to become enlightened!” Or, “I’m a bad person for feeling this way – I must get rid of my anger… etc. One becomes attached to desire by reifying it and personalising it instead of seeing it as something impermanent, unsatisfactory and not self.
The Buddha advised us to end suffering by letting go desire. But ‘letting go’ desire isn’t a deliberate act; that would be more akin to rejection, repression or denial of lust/aversion/boredom – neither pleasant nor healthy! Rather, the urge to pursue what may at first sight seem to be a source of pleasure or pain gradually fades when one is mindful enough to recognise it as something impermanent, unsatisfactory, not ‘I’ or ‘me’ or ‘mine’. As one continues to practice, the conditioned pleasure seeking/pain avoiding habits of a lifetime increasingly lose their appeal and so one is less inclined to indulge them. The attachments loosen over time and one eventually realises that a once familiar desire has been let go and there is no more suffering. But the letting go is a natural and gradual process – a result of clearer seeing – rather than something that is done intentionally.
Actually, to want rid of desire is to be dissatisfied with reality; the dissatisfaction arises from grasping at delusions of self and ideas about how things “should be” and it results in a mind that is troubled rather than a mind at peace with the way things are. However, until one has fully mastered the art of clear seeing that recognises anicca, dukkha, anatta in all things it is most important to guard the senses against excessive sights, sounds, smells, tastes and tactile sensations – because too many pleasant ones will undermine one’s resolve to practice and too many unpleasant ones will undermine confidence in the teachings. 
As a lay practitioner with householder responsibilities I know just how hard it can be to stop pondering unanswerable questions, to stop dwelling in past or future or worrying over problems that are beyond my ability to resolve, and to resist distractions (alcohol, music, newspapers, television, internet forums… etc.) that cause heedlessness. But the more practiced I get at watching desires arise and develop and subside naturally – without attaching/absorbing into them or pushing them away – the less attractive or compelling they seem. Many activities that I once believed to be essential for happiness have since lost their appeal. They haven’t been rejected as such, but neither is there any heartache in not pursuing them. That some longstanding desires have indeed been let go is obvious when I compare my actions now to my actions when I first started practicing.
 Paul L, ‘Desire’. <http://trustinginbuddha.co.uk/desire/>
 Yuttadhammo Bhikkhu, ‘Good and Evil’. <http://www.youtube.com/watch?v=7EwyLLlLhWU>
 Yuttadhammo Bhikkhu, ‘Ask A Monk: How to Stay on the Middle Way?’ <http://www.youtube.com/watch?v=hpmKgTD3FLY>
 Venerable Ajahn Sumedho, ‘The Four Noble Truths’, (Hemel Hempstead: Amaravati Publications, 1992), p. 29.
 ibid p. 31.
 Paul L, Sabbasava Sutta <http://trustinginbuddha.co.uk/sabbasava-sutta/>