Even if you only have 60 minutes to exercise during the work week, you can train for the half or full marathon. The minimum is actually better for reducing injuries. During the week, you only need to accumulate an hour of running/walking. The long run/walk starts at three miles and gradually increases by one mile each week until it reaches 10 miles. Then, you’ll do the long on every other week, with a run/walk of half the distance on the “off” weekend. After half or full marathoners complete the nine-miler (half)/18-mile (full), they’ll receive two easy weekends for good behavior, shifting to a long one every third week.