A very brief daily prayer each day for nine days. For the more ambitious, say a Divine Mercy Chaplet also (I can guide you to some very good ones, audio or video, if interested). There is also a link at the following site.
Today bring to Me the Meek and Humble Souls and the Souls of Little Children, and immerse them in My mercy. These souls most closely resemble My Heart. They strengthened Me during My bitter agony. I saw them as earthly Angels, who will keep vigil at My altars. I pour out upon them whole torrents of grace. I favor humble souls with My confidence.