Hoping 15 miles on Saturday won't kill me

My seven miles last night was a mixed bag. On the positive side, my hip didn't hurt at all. Excellent. My toe hurt a few times, but mildly. Good. On the negative said, my right leg hurt last night. WTF? Assuredly not good. I'm just praying that it was getting sick of compensating for a weak left leg, and that now I'm working on the left leg the right will stop complaining. Either that or I'm taking up swimming. Seriously. I pretty much told myself that I would train as long as it was fun and I wasn't hurting myself. I had and have every intention of finishing the marathon, but not at the risk of doing long-term damage to poor little legs. They're trying hard, but I have to respect that they might have limits under 26.2 miles. I don't want to...but if it comes to that I will swallow my pride and throw in the towel. Of course that will be my absolute, dead-last resort, because I have a feeling that my legs are a lot less sensitive than my ego.