On a more serious note, the root cause of attachment is ignorance. The monkey had placed a greater value on the banana than its own freedom. To let go of the banana, it must exercise conscious detachment from the object of desire (a banana in this case). You consciously detach yourself from something for a few weeks and detachment happens automatically. You quit drinking tea, for example, for a few weeks and the desire to have tea will go away. Try it to believe me.
