'Act' in the Bible

When you hear the sound of marching in the tops of the balsam trees, act decisively, for then the Lord will have marched out ahead of you to attack the camp of the Philistines.”

So Joab sent someone to Tekoa to bring a clever woman from there. He told her, “Pretend to be in mourning: dress in mourning clothes and don’t put on any oil. Act like a woman who has been mourning for the dead for a long time.