Half-marathon at 6pm?!?!...That's gonna suck to be honest. I've noticed myself that I don't enjoy my training runs in the evenings as much as I enjoy my runs on a Saturday morning or lunchtime. Of course, I am doing all of my midweek training runs on the treadmill, so that could lend to my impending sense of doom.
What training program are you doing? I only took up running about a month ago. My buddies were going to Miami for the ING marathon, and I had always wanted to go to Miami, so I foolhardedly said I would do the Half with them. Even though I had never done endurance running before, I decided to do a program call the F.I.R.S.T. program. It comes from the Furman Institute of Running, or some such, you can find it on Runner's World. I'm enjoying it because if only calls for 3 mandatory running days: long, tempo, and speed. I'm allowed do crosstraining 2 other days. Currently, I am only doing 1 day of crosstraining, and I'm counting the hurling training session I go to on Sundays. I've gotten a completely new lease on life there. Not doing too bad for 35 years of age. Good luck on your half-marathon!!! Keep me posted. In addition to the Miami half, I am thinking of the doing the Atlanta Half in March, and the Bay Run from Bantry to Glengariff in May.