MARATHONS AND MOTIVATION

I really don't know where to start. It's been so long since my last entry. I guess I'm just wondering about Motivation, how do you get it? How do you lose it? In my last entry appropriately titled NO DOUBT, I talked about how motivated I was. So I guess this one is about well.....DOUBT! I'm 7 weeks away from my planned Jacksonville marathon. I pulled a hamstring running a half marathon several weeks ago. I set a new PR and was very happy with my performance. The hamstring is feeling much better now, NOW it's my left knee that's bothering me. We think it is ITB, known as IT Band syndrome, which really in your hip but the pain is in the knee. Anyway it started about 2 weeks ago on my long run of 16 miles. I had to walk a lot and was in severe pain. Like most runners, I'm running through it with just a few days here and there off.
But what worries me even more is that I feel like my long run distances are no where near as many or as long as they have been in my last two marathon training programs. I really haven't had one good long run, NOT ONE!! That's really bad, with only 7 weeks to go. I'll try for an 18 miler this Saturday with some friends.
I emailed my Rock Star Coach, and he says give it 2 weeks and see how I feel, but he's really talking about the knee pain, not the DOUBT about where I am in my training and if I'm ready to set a PR in Jacksonville. I will not be happy with anything other than a sub 4:30 marathon. (btw, this is fast for me so don't laugh if you're thinking "you" could do that in your sleep). 
 
So I am struggling as whether or not to drop out of Jacksonville. I have not signed up yet, not made airfare reservations, nor hotel, etc. Jacksonville does not sell out so I have the Luxury of waiting to make a decision. Maybe this is bad, if I'd paid and made all the arrangements like I have in the past maybe I'd be more committed, or feel different. I really don't know. I guess things change drastically when you are shooting for a PR time and not just to finish. I know I can finish, I just don't want to be miserable the last 6 miles or more like I was in Paris. So I have really no answers! It's very difficult when I have so many Milestones Jewelry Expos coming up and we are so busy. But that's a good thing. Well I guess I will just keep putting one foot in front of the other and come to a decision. I'll keep you posted.
"Only those who will risk going too far can possibly find out how far one can go". ~T.S. Eliot