Poison is what goes beyond our need.

Life is based on the idea of balance between a need and what satisfies that need. True satisfaction should match the pain caused by the need. Hunger, for example, is satisfied with enough food and anything beyond that becomes a kind of suffering. It is the same with other basic needs like sleep and sex.
The philosopher Rumi expressed this idea in a simple way:"Poison is what goes beyond our need."
This idea of balance can grow into a wise way of living.