The choice of the three O’clock prayers depends on individual circumstances – you can follow Jesus’ advice given to Sister Faustina:
My daughter, try your best to make the Stations of the Cross in this hour, provided that your duties permit it; and if you are not able to make the Stations of the Cross, then at least step into the chapel for a moment and adore, in the Most Blessed Sacrament, My Heart, which is full of mercy; and should you be unable to step into the chapel, immerse yourself in prayer there where you happen to be, if only for a very brief instant. (1572)
Little prayers for use at the Hour of Great Mercy:
– You expired, Jesus, but the source of life gushed forth for souls, and the ocean of mercy opened up for the whole world. O Fount of Life, unfathomable Divine Mercy, envelop the whole world and empty Yourself out upon us. Amen. (1319)
– O Blood and Water, which gushed forth from the Heart of Jesus as a fount of mercy for us, I trust in You! (84) (Repeat three times)