Conscience
Most people don’t seem to think of conscience as knowledge, while that is exactly what it truly is. It isn’t behaviour, it isn’t action; it’s knowledge.
Etymology
The word Conscience is derived from the Latin prefix Con- which means "Together, or with" and the Latin verb Scire which means "to Know, or to Understand". Those two words combined mean "to Know together". Therefore:
Exercise of Conscience (Action)
The exercise of conscience is the free will choice of right action over wrong action; once the definitive knowledge of the objective difference between right and wrong according to Natural Law has been acquired and integrated into the being. We must acquire that knowledge first, come to an understanding of it, and finally we act either in accordance with it, or in disharmony with it. If we act in accordance with it, that is called the exercise of conscience.