Before You Start: You need a solid base before you take on half marathon training. You should be running at least three times a week: Weekday runs should average about 30 minutes, and your weekend long run should be up to at least three miles.
Target the Long Run: Every other week, increase your long run by 1.5 miles until you’re run/walking 13 to 14 miles. On alternate weeks, keep your long run to no longer than three miles. Your longest long run should fall two weeks before your half-marathon. Plan to take about 15 weeks to prepare for the big day.
Strike a Balance: Keep your weekday runs to no longer than 30 minutes. If your goal race is hilly, do one of those runs on hills. Vary your pace depending on how you feel—but do try to mix in some speed to boost your fitness. Experiment with your run/walk ratio, gradually adding time to the run segment over the course of your training. On nonrunning days, do easy cross-training like walking, swimming, or cycling, or simply rest up.