Junk miles and recovery runs are important elements of a good
training program as they can help you run faster and longer. They
allow you to enjoy slow easy runs while your body is healing from
the stress forced upon it in the hours before you hit the road and
they allow you to reach some whole number goal of daily or weekly
mileage to appease the guilt you might carry for running below a
self made threshold of distance that you consider significant and a
source of pride.