Damn, after quit running for a couple of years I just started jogging again today and I nearly kill myself. I was doing fine after 2 miles, but on the way back I started to get tired and continue anyway. When I was active, I am used to running about 8-10 miles a day (I was in the cross country team in highschool). Once I got to the front porch, I stopped and suddenly everything turned pitch black. I guess I blacked out and nearly collapsed onto the brickwall with those sharp iron grids. I quickly reacted and grab the grids with my hands. I layed on the ground for about 10 seconds before I regained enough strength to get up and went in for some water. Moral of the story? Do not attempt pushing yourself like I did even if you used to be a top notch jogger who has been inactive for a while.