Not what the OP asked. But here we go.
Running has high impact on the body due to the forces involved in throwing your entire mass into the air and then stopping the fall on a single foot. There are alternative exercises that accomplish similar goals while putting less stress on your body.
The only reasons you should be running are: 1) you are in the military or a related profession where running is a job requirement, 2) you are cross-training and need a little bit of high-impact exercise to round out your development, 3) you are running late on a portion of your transit commute and you think looking disheveled and out-of-breath will garner more sympathy from the people you have disappointed
As I said before, running recreationally is for masochist pickme's.