"Metta practice is the cultivation of our capacity for lovingkindness. It does not involve either positive thinking or the imposition of an artificial positive attitude. There is no need to feel loving or kind during metta practice. Rather, we meditate on our good intentions, however weak or strong they may be, and water the seeds of these intentions. When we water wholesome intentions instead of expressing unwholesome ones, we develop those wholesome tendencies within us. If these seeds are never watered, they won’t grow. When watered by regular practice, they grow, sometimes in unexpected fashions. We may find that lovingkindness becomes the operating motivation in a situation that previously triggered anger or fear."
from Gil Fronsdahl's 'May We All Be Happy'
