One, let God decide for us. Here the Spirit attracts our will so strongly to a course of action that leaves no doubt what God wants of us. Perhaps a conversion experience or a moment of enlightenment. However, this is not the usual way we discover God's will.
Two, let us decide for ourselves. When there is great uncertainty concerning God's will, St. Ignatius suggested two methods. First method, after prayer for light and courage, we use our understanding to weigh the matter with care, enumerating the advantages and disadvantages of each alternative, basing our decision on what is most pleasing to God.
Second method is to use our imagination: one, consider what you would suggest to another person facing the same decision which you now face; two, imagine yourself on your deathbed or at your final judgement and ask yourself what you would have then decided. In each case, we are trying to shed some light on our confused situation by imaginatively distancing ourselves from it.
Three, let God confirm our decisions. To use our natural powers to make our decisions for ourselves when there is great uncertainty concerning God's will is not wrong, but it is incomplete, according to St. Ignatius. He synthesized the way of God deciding for us and the way of our deciding for ourselves, and created the third way of making a decision. It is the way of discernment — when we seek the Spirit's confirmation of decisions which we have made based on reason alone.
Here is what we do. We treat as tentative our decision made by means of the rational or imaginative methods. Next, we present the decision to God for his confirmation and patiently wait. And how will God confirm it? St. Ignatius describes it this way: "…much light and understanding are derived through the experience of desolations and consolations and the discernment of diverse spirits". That's the next topic.