On the occasion of the visit of the relics of Saint Claude La Colombière to Ireland in 2006, Father Bernard McGuckian, S.J. prepared some remarkable resources, including a biography of the saint, a selection of quotations, and a number of his prayers. Among the latter is this one addressed to the Divine Mercy. I know that it will speak to the hearts of many.
Prayer to the Divine Mercy
O Lord, behold here before You a soul who exists in this world in order to allow You to exercise Your admirable mercy and manifest it before heaven and earth.
Others may glorify You through their faithfulness and perseverance, thus making evident the power of Your grace. How sweet and generous You are to those who are faithful to You! Nevertheless I will glorify You by acquainting others with Your goodness to sinners, and by reminding them that your mercy is above all malice, that nothing can exhaust it, and that no relapse, no matter how shameful or criminal, should allow the sinner to despair of forgiveness.
I have offended You grievously, O beloved Redeemer, but it would be still worse if I were to offend You by thinking that You were lacking in enough goodness to forgive me. I would rather be deprived of everything else than the trust I have in your mercy. Should I fall a hundred times, or should my crimes be a hundred times worse than they actually are, I would continue to trust in your mercy.