Preparing for the long run

I have been hydrating, increasing my mileage during my morning runs, etc to get ready and attempt a 7-8 mile run this weekend. I know I will have to decrease my pace and be ready to take almost 2 hours, but I am curious how my body will react to the stress. I'm doing 4+ miles in the mornings now and I know I'm increasing my weekly mileage quite a bit and trust me my calves are letting me know it! I'm aware they are there! So it's Wednesday, I missed a short run this morning (30 minutes) but Laure is letting me borrow her jogging stroller, so I'm going to try and get a 30 minute easy run in tonight so I will be OK for tomorrow!