Actual grace is God’s temporary enlightenment of our mind or strengthening of our will to perform supernatural actions that help us obtain, retain, or grow in sanctifying grace. For instance, God may give us actual grace that strengthens our will to go to Daily Mass. If we do go, our attendance and reception of the Holy Eucharist strengthens our sanctifying grace.
Actual grace with which we freely consent to cooperate is called efficacious grace, because it accomplishes God’s purpose in granting it. Actual grace to which we freely refuse consent is called sufficient grace, because it would have been sufficient to accomplish God’s purpose. Our decision to cooperate or not cooperate belongs to the will.