That may be true, but sometimes when I don't have the words pray on my own it's helpful to have those written prayers. Especially when the written prayers make you think about and ask for things that are really rather difficult to pray on our own.
The following is a prayer written by Saint Maria Faustina (1905 - 1938). We prayed in a special service I went to on Sunday afternoon.
It touched me and challenge me:
Oh Most Holy Trinity! As many times as I breathe, as many times as my blood pulsates in my body, so many thousand times do I want to glorify Your mercy.
I want to be completely transformed into Your mercy and to be Your living reflection, o Lord. May the greatest of all divine attributes, that of Your unfathomable mercy, pass through my heart and soul to my neighbor.
Help me, O Lord, that my eyes may be merciful, so that I may never suspect or judge from appearances, but look for what is beautiful in my neighbor' souls and come to their rescue.
Help me, that my ears may be merciful, so that I may give heed to my neighbors' needs and not indifferent to their pains and moanings.
Help me, O Lord, that my tongue may be merciful, so that I should never speak negatively of my neighbor, but have a word of comfort and forgiveness for all.
Help me, O Lord, that my hands may be merciful and filled with good deeds, so that I may do only good to my neighbors and take upon myself the more difficult and toilsome tasks.
Help me, O Lord, that my feet may be merciful, so that I may hurry to assist my neighbor, overcoming my own fatigue and weariness. My true rest is in service of my neighbor.
Help me, O Lord, that my heart may be merciful so that I myself may feel the sufferings of my neighbor. I will refuse my heart to no one. I will be sincere even to the who, I know, will abuse my kindness. And I will lock myself up in the most merciful Heart of Jesus. I will bear my own suffering in silence. May Your mercy, O Lord, rest upon me.
You yourself commanded me to exercise the three degrees of mercy. The first: the act of mercy, of whatever kind. The second: the word of mercy - if I cannot carry out a work of mercy, I will assist by my words. The third: prayer - if I cannot show mercy by deeds or words, I can always do so by prayer. My prayer reaches out even there where I cannot reach out physically.
O my Jesus, transform me into Yourself, for you can do all things.