With dd, I had a handful of peaceful, meditative, *opening* mantras planned. What I ended up repeating to myself through the better part of 18 hours was "This is gonna hurt, this is gonna hurt, this is gonna hurt, but then it gets better." That was just long enough to get me over the peak of the contraction.
With ds, I didn't plan anything. And what I ended up repeating, to myself and out loud, for the half hour or so at the end when I was too into it to keep doing funny horse lips was, "Come on, Sebastian, I want to meet you, come on, sweetie, time to come out . . . Come on!"