Sometimes, when I am in such a state of spiritual dryness that not a single good thougth accurs to me, I say very slowly the Our Father and the Hail Mary; and these prayers suffice to take me out of myself.
It is a comfort to remind ourselves that we don't have to make up long, elaborate and lengthy speeches to God, imploring him to come to our aid. This is especially helpful in times of spiritual dryness, or even just basic weariness. The Our Father, the prayer Jesus himself taught, and the Hail Mary, when we remember the Archangel Gabriel's salutation and invitation to Mary, will suffice. When we pray these two prayers, we pray with Jesus and Mary, which is always more than enough.