Getting up hills... before TOMRV which has a lot of them, I memorized a wonderful song about a widow who lived on the moor who never turned a traveler from her door ... who had more endurance than the devil, who could not last the night with her. (At sixty-nine the widow laughed... "again, again!" she cried... the devil said, "well I can see just how your husband died.")
So the ride comes along and I'm chugging up the hill... and the song that comes out is "Ain't no grave gonna hold this body down!"
THe other thing I tell myself when the little voice starts to question whether I can do something (especially keeping up with a fast pace) is "well, of *course* you can't do this. What a completely absurd notion! I fully agree! You just can't stop right NOW!"
I observed that when I was in the middle of thinking "I can't keep up with these guys" that I was holding my body tensely and when I said, "no, ride like you know what you're doing even if you can't" - kinda calling on the Marine idea of *looking* like you're not trying - d'oh, I went faster.