Gray Hair Sends Woman Into Tailspin

I found my first gray hair today. I'm not really concerned about having gray hairs as such, but the fact of it put the reality of my finite lifetime and disappearing youth into sharp focus. Obviously I always knew I was getting older, but now I know for certain that from now on there will not be a time when I do not have gray hairs. A big fat reminder of this forward march toward death. Not to be melodramatic or anything but I'm mildly distressed. Also I can't seem to bring myself to do my Trial Ad homework even though class is in 1-1/2 hours and I have done nothing to prepare for the ten minute opening statement I have to give. I skipped Tax because I was feeling mopey. I am 50 pages into Ian McEwan's book, Saturday, and am not enjoying it. (Does anyone know if it gets better, or should I just chuck it? I hated the last book I read by him, Atonement.)