Also: Restraint, Self-Control
Forbearance or self-control is the ability to exercise restraint, to stay in balance. It is disciplining yourself to be measured and temperate in your response to trying circumstances. It is being patent and even keeled while enduring hardships. It is having the ability to constrain your own worst impulses and allowing thoughtful, wiser aspects of yourself to govern what you say and do.
Just because we can do something doesn't mean we should. Forbearance protects us against doing harm on impulse in the throes of anger or fear. Since so much of virtue is about finding a balance point between two kinds of excess, forbearance helps to keep us close to the center of our better selves.