This Mileage Building Training Plan is designed to help build you from 20 miles to 40 miles over a course of 12 Weeks. You will slowly build your mileage with the proven 3 weeks “build”/1 week “step back” concept. Including a stepback week in mileage is key to staying injury free as you build your volume across the plan. Use this plan to build your base and get ready for your next race-specific plan. Before starting, you should be able to run 4 miles on your regular runs and at least 10 miles ...