Taking a day off helps to prevent overuse injuries, restores your glycogen stores, and prevents mental burnout. How "off" do you need to be once per week? You should be off completely, or 20 to 30 minutes of running below 60% of max heart rate (if you simply cannot stay away from your running shoes).
You should also include an easy day into your weekly routine. It helps to build base, improve endurance, and increase blood volume. An "easy" day should be 70 to 75% of max heart rate or conversational pace at a comfortable to moderate effort.
Keep reaching for life's mileposts!
The P.A.C.E. Fitness Foundation, Inc.
P.A.C.E. is a non-profit organization aimed at Promoting Active Children Everywhere.