When we desire what do not have and find fault with what we no longer desire we lose our way. When we do this, we give externals more value than they deserve. When we allow things to be our rulers we hand over our own self-worth and in kind become a thing. We turn ourselves inside out and thus become an external to ourselves.
Contrary wise, when we take great pains to avoid something that does not bring us pleasure; we imbue this thing sovereignty over our joy and tranquility. We become detached to our moral and ethical moorings to put daylight between something and us that we give value to avoid. This too is desire and this too creates suffering.
If we avoid that which we causes us discomfort but falls within our domain of our control, we suffer not. However; if we run from the inevitable that is in the realm of the external we injure ourselves and those around us. Likewise desiring that which is obtainable, within our control serves us well as long it serves all and the greater good and helps us buoy our peace of mind and self-worth. However, desiring that which is beyond the internal that bring us pleasure invites misfortune and calamity.
Be careful what you wish for and what you wish not. When we do not get what we want we are disappointed and when we get what we do not want we are displeased. Desire and aversion are the two sides of the same coin. It is problematic when we use this coin to predict and govern our lives. If we can recondition ourselves to not let this be a habit, and instead deal with and accept the things that are within our control and not be subjected to the whims of the mercurial wants and needs of the external world, we accept our sovereignty over our joy and happiness.
There may be times when it is appropriate to desire or avoid something. At these times, let us use our best judgment to discern the most objective path to take.