The September races are my favorite! The weather is perfect for them.
It's really hard to train for the first one because you're not sure what to expect. Do you have any 10 miler races in your area? I did one of those before I ran my first half marathon and it really helped. In my mind I just had to think that if I could finish the 10 mile race, I only had a 5k more to go after that.
It gets easier to stay motivated to train once you experience the gathering in the cattle fences, the national anthem, the start of the race, the conversations you have with total strangers throughout the race, everyone running their own race but still working toward the same finish line, the volunteers and spectators with their posters and cheers the whole time, hitting the last mile, sprinting in to the finish, getting that medal around your neck, snapping a photo at the photographers stand, heading to a HUGE post-race breakfast....
I still get emotional at every single long race I do. There's something very cool about the feeling that NO ONE helped you get to the finish line, you did that on your own, and no one can ever take that away from you.
Lol sorry for the long reply, it's just that cool. Good luck with your training! Keep me posted when you get signed up for the next race, I can't wait to hear how it's going!