All our mental sufferings are caused by selfish desires for pleasure. Think about that. They are caused by the desire to be what we are not, to have what we do not have, and not to have the things we already have. If we think hard and long about it, there is no denying that the chief culprit in our inability to enjoy a sense of happiness is desire.
What is fear but the desire to avoid; greed, the desire to have; jealousy, the desire that others shall not have; grief, the desire to regain something or someone. All our negative emotions can be worked out in terms of desire, the chain that binds us. The only way to avoid this restlessness is to reduce or get rid of the desire that causes it.
~ K. Sri Dhammananda