"It is a virtue for a Christian to be full of prayers in their lives". "Your conscience is a good conscience, if you know how to pray for others". These words are secret knowledge.
God wants us to be prayerful because it is the sign of submissiveness. Prayer places us in the position of talking to our heavenly father directly. Because he wants to hear from us. He wants us to talk to to him thereby drawing closer to him.
While talking to him, we make requests, we give thanks and we also intercede for others. That's why the teacher made that statement, that if you can pray for others, then, You have a good conscience. Therefore prayer is always the key!