The first is an ancient prayer popular among Orthodox Christians. It comes in a few minor variations and is often referred to as the Jesus Prayer:
Lord Jesus Christ, Son of the living God, have mercy on me, a sinner.The second is a prayer revealed to St. Faustina, typically prayed as part of the Chaplet of Divine Mercy, and again quite simple:
For the sake of the sorrowful Passion, have mercy on us, and on the whole world.The final prayer for mercy comes from Fatima, and against reflects the them of praying for ourselves and others:
O my Jesus, forgive us our sins, save us from the fires of hell, lead all souls to Heaven, especially those most in need of Thy mercy.These are prayers you can easily insert into your day. Please pray them, often. Look around - we need them.