Prayer is an act of love; words are not needed. Even if sickness distracts from thoughts, all that is needed is the will to love.
Mental prayer in my opinion is nothing else than an intimate sharing between friends; it means taking time frequently to be alone with Him who we know loves us. The important thing is not to think much but to love much and so do that which best stirs you to love. Love is not great delight but desire to please God in everything.
Be gentle to all and stern with yourself.
All things must come to the soul from its roots, from where it is planted.
For prayer is nothing else than being on terms of friendship with God.