You guys know that feeling where you're almost done with that last interval? You can see the light and the end, but you're not sure you're going to be able to make it... and then you do? That's a good feeling.
Back in my HS track days, we would do 10x400m 5 or 6 times a season. Coach always said the last interval was the easiest, 2nd to last was the hardest. That mentality has always stuck with me.