Marathon update and lessons learnt!

This is my last week before my 10K(6 miles) race on sunday and I feel excited and scared at the same time. Till today I have run the whole 10KM distance only once during my training. My usual distances are 4miles(a little less than 8KM) and I do that with little discomfort. Last weekend I attempted my first 10KM distance and struggled for the last 1 KM. I finished it huffing and puffing. I might run the whole distance twice this coming week and take rest the last 3 days before the run.
The Marine Corps Marathon is a very prestigeous event and the 10K portion of the marathon has been popular among people who want to run but cannot run the whole marathon(26.2 miles) or half marathon distance(13.1 miles). Often, a 10K is the starting point for a lot of beginning runners(5K is another place where you can begin). People line up along the spectator stands early before the race starts and cheer for runners all day. Its one thing running for yourself, its another to cheer some person who don't even know, to keep going! I will do a full post on my 10K marathon running expereinces and how the crowd was.

I am terribly slow. The other day there was this guy running on my neighboring treadmill in the gym and he seemed to be struggling with it. From the looks of it, it seemed to me that he was running a moderate pace. I was diong a 5mph pace and thought he must be doing something similar too. I glanced, stealthily(yeah, I know it is a bad habit!!), at his treadmill dashboard and almost fell off mine! He was running a 7.5 miles and hour pace and it didnt even seem like that! After that shock, now I stick to looking at my own dashboard instead. Even at that low speed, running feels very energizing in so many ways. One being the adrenalin that is pumped because of the workout. Another reason is that running makes me feel like I am overcoming my weaknesses. I am a slow runner and my reflexes are poor so I cannot play a game like Tennis or Squash with someone who can play well and that makes me feel a little inadequate but being able to run 40-45 minutes without feeling it makes me forget those inadequacies!
Is there any workout/activity that makes you feel energized?