The following is an article and explanation from Fr. Mark Thibodeaux, SJ:
In the Examen, we review our recent past to find God and God’s blessings in life. We also look back to find moments in the day when things didn’t go so well, when we were hurt by something that happened to us, or when we sinned or made a mistake.
We give praise and thanksgiving for the blessed moments. We ask for forgiveness and healing for difficult and painful moments. Having reflected on this past day, we then turn to the day yet to come and ask God to show us the potential challenges and opportunities of tomorrow. We try to anticipate which moments might go one way or the other for us: toward God’s plan or away from it.
We ask for insight into what graces we might need to live this next day well; patience, wisdom, fortitude, self-knowledge, peace, and optimism. We ask God for that grace, and we trust that he wants us to succeed in our day even more than we do.
That’s the basic idea behind the Ignatian Examen.
St. Ignatius Loyola would say that this should be the most important moment of our day. Why? Because this moment affects every other moment.