Training for WDW Marathon 2014

By now, everyone should have started training for the marathon. My training plan started two weeks ago and I have already derailed. This is bad, very bad. My sister put together my plan so I could finish in the 5 - 5:30 range. I am doing ok with the short runs and keeping pace, but the long run on Sunday gets me everytime. Well it go me once, this past weekend I skipped my run to do a 12 mile hike and decided that should suffice. But here I am Tuesday and not back running. I woke up on time, just was too content in my bed to actually go run. I have four runs a week until November when I switch to five, so you would think it would be easy to do. However, something about seeing a number higher than a three on my calendar spooks me and I chicken out. This cannot happen. I want my goal time. So I ask, what do you do when you see yourself slipping on training? How do you stay motivated in colder morning weather?