Mental prayer consists of what was explained: being aware and knowing that we are speaking, with whom we are speaking, and who we ourselves are who dare to speak so much with so great a Lord. To think about this and other similar things, of how little we have served Him and how much we are obliged to serve Him, is mental prayer. Don’t think it amounts to some other kind of gibberish, and don’t let the name frighten you.
-St. Teresa of Avila