Training for a marathon? What?

Yes, yes I know. Looking at me probably doesn't cause you to think, "she's a marathoner." But it's the truth!
A few months back I began running just to get some more cardio in my life...and for some reason this time around I actually enjoyed it...unlike a few attempts I've made in the past. I think this time I enjoyed it because I stuck with it long enough to actually start seeing real improvements: my distances got longer, my pace picked up, I didn't hurt as much, my body toned up, my muscles got stronger and I just felt better overall. Sometime in April I began reading a book about how to train for a marathon and this book I will largely give due credit: "The Non-Runner's Marathon Training Guide" by David Whitsett. I HIGHLY recommend this book to anyone who wants to try running distances without dying. I am absolutely not a distance runner by nature, but this book truly gave me the confidence to get out there and try! And not die!
I just began week 5 of the 16 week training program, and decided that somehow I need to document these efforts. During the last couple of weeks of training I've begun to realize how this just may be the most physically demanding challenge I've ever tackled, and I think a mental outlet will be a fantastic element to add to my training. The training program calls for running 4 days a week: 2 shortish days, 1 average day, and 1 long day. Each week gradually increases the number of miles ran by 2 or 3 miles and that usually takes place within the average and long training run days.
Last week during week 4 consisted of: 3 miles, 5 miles, 3 miles, and 8 miles.
This week, week 5 consists of: 3 miles, 5 miles, 3 miles, and 10 miles. (But actually I'm upping this week a bit because I'm going to Michigan during week 6 and don't expect to be able to get all the miles in. )
I won't go back and recap all my most recent runs except for last Saturday's 8 mile run. On this run I discovered my personal Doomsday Hill...this baby is the mother of all hills. HUUGE. As soon as I started running down it I began thinking "ohhh nooo"...knowing that I was gonna have to run back up it. On my way back I hit the hill...and soon enough it was over! I made it up! When it was over I realized what a mental barrier this stupid hill had created in my mind. The miles leading up to running back up the hill were labored and slow, but as soon as I crested the hill, my run got easier! I accomplished so much during that quarter of a mile or so, I was super proud of myself for doing it, it made the last couple miles seem like cake.
I'm beginning to really learn the significance of mental imaging, and positive thinking: today during my 4 mile run I practiced some positive mental images ( I know it sounds super dumb, but it's not) and I think it worked! The mental aspects of running take just as much practice as the physical aspects; I know I've heard that a gazillion times, but I think I'm actually starting to experience what it feels like.