Take a break if you have been training hard for 4-6 months straight
If you have not run in over a month gradually build up your mileage
If you are sick, do not run
If you are injured not run
Vary your runs in terms of distance, hills and pace
Be consistent in your training
Each week run 3-6 days per week depending on your fitness
You can do core exercises 2-5 times per week (Very Important)
Do circuit training for general strength work
Have fun