Answer: If you can already run 3 miles, then give yourself 12 weeks to train for a half. If you can't run 3 miles, then start with a Couch to 5K (C25K) program and work up from there. Most C25K programs take you from zero to 3 miles in eight weeks. After you reach 3 miles, give yourself at least 12 additional weeks to train for 13.1 miles.
