A Retreat Letter is a letter written usually by a family member or friend to a retreatant, person attending a retreat. The letter is usually a secret and given to the retreatant to read during a time of deep contemplation, and personal reflection. The letter should be encouraging, and inspiring. It could be as detailed a sharing a personal story, maybe telling the retreatant the things you admire about him/her, or as simple as sharing a favorite bible verse or saying and ending with well wishes.