Mondays and Fridays: Mondays and Fridays are rest days. Rest is critical to your recovery and injury prevention efforts, so don't ignore rest days. Your muscles actually build and repair themselves during your rest days. So if you run every day without taking days off, you won't see much improvement.
Tuesdays and Thursdays: Run at a comfortable, conversational pace for the designated mileage. If you feel good during the last mile.