Prayer

I am increasingly convinced that the word prayer, which has become a functional and pious thing for all believers to do, is in fact, a descriptor for inner experience. That is why all spiritual teachers mandate prayer so much. They are saying, "Go inside and know for yourself!"...As Jesus graphically puts it, prayer in "going to your private room and shutting the door and [acting] in secret." (Matthew 6:16)"
From Hidden Things: Scripture as Spirituality
by Richard Rohr