Why we have desires and how do we control them?..
Lets first understand how desires are formed. Desires are a culmination of thoughts. They begin when we meet someone or see a particular object etc. Now try and understand the process from induction of thought to culmination of desire.
Now for instance you are hungry. Now do you simply quest your desire to eat by eating a salad??
No you start thinking about your favourite food items, how you felt when you last ate it, you remember those McDonalds advertisements showing that juicy burger and fries!! Yummm!