Brain Power

While on my run this morning I was really feeling like I wanted to stop or faint, most likely both if it came to it. But then, and this happens often, I rounded the corner down the road that meant the last mile to home and  slowly this wave of energy overcame me. My pace went from what seemed like 12 minute miles to about 8 minute miles. I see two reasons for this, one is because it is a downhill and two is that I seem to get this high from almost being done with a workout. No matter what I am doing I always get this sudden burst of energy and feel completely fine right near the last few minutes of a workout. This disappoints me in a number of ways! Should I lengthen my run? No because if I do that I will no longer be near the end and this feeling will go away. Did I have this energy the whole time? I had to have, but how does it allude me for 2.5 miles and decide to show up at the end? And then I started to wonder about the human mind and mental will power. Could it be like that feeling before people die, when their body knows it's over and they make a miraculous recovery for a couple days? I feel like the human mind is capable of so much that we don't even realize. It is said that we generally use about 10% of our brain throughout our life. So what about the other 90%? I want to tap into that brain power. There has to be something there that I can use...