I love writing the first line of a novel because you have all this unused shine bottled up in you that is just bursting to make it onto the page. If I ever find myself NOT excited to begin a novel, I have to question if the idea is ready to be written.
I also hate writing the first line because it can so easily sound forced. I've read many a first line that almost seems to scream I'M A FIRST LINE, I NEED TO GRAB YOUR ATTENTION WITH HEART-POUNDING CONFLICT AND TENSION AND INTRICATE STYLE AND OH, WHILE WE'RE AT IT LET'S THROW IN SOME WORD-BUILDING.
And let's not forget the really short first lines, the one-worders, because they act toward the same effect: STOP. I'M AN IMPORTANT STANDALONE. I GRAB YOUR ATTENTION. LOOK AT ME.