Litanies are prayers with responsive petitions (such as “Holy Mary, Mother of God / pray for us”). At first glance they seem to be rather repetitious, but consider that Psalm 136 is also repetitious (it keeps repeating “for his steadfast love endures for ever”). Repetitious prayer is not bad; we just need to work to avoid rattling off prayers mindlessly, without trying to pay attention to our prayer.
The Litany of the Blessed Virgin Mary (the Litany of Loreto) is probably the best-known Marian litany. It has many beautiful titles of Our Lady. (The image above is a symbol of one of her titles, Queen of Virgins.)
With this lovely litany, call upon Our Lady for her powerful intercession in your life!