Some time ago I found this definition of prayer and it just struck me as one of the most beautiful defintions I have ever heard.
One should never underestimate the power of prayer as a response to situations in our lives. To use a simple definition, prayer is our love joined to God's love, and that love visits the person for whom we are praying. Even if people do not know that we are praying for them, the power of prayer is still communicated at a spiritual level. We often sense that something is happening even when no words are spoken (e.g., when someone is angry at us, or when something painful has happened to a loved one). This is the level at which prayers have their effect. Even if we never tell the loved one that we are praying for him or her, that person senses it at a profound level. We are embracing that person in our love and God's love and love always brings healing.
Our prayer and God's mercy are like two buckets in a well; while the one ascends, the other descends.