Build from week 1 – 30 miles, week 2 – 34 miles, week 3 – 38 miles, week 4 – 32 miles, week 5 – 37 miles, week 6 – 42 miles, week 7 – 47 miles, week 8 – 40 miles, week 9 – 45 miles, and week 10 – 50 miles. In each week you increase the mileage, except in weeks 4 and 8, in which you decrease.