How long will it take me to train for a marathon?

It depends on your goals! Many runners training to finish a marathon can do so with only 12 weeks of training, but if you are aiming for a PR or to qualify for the Boston Marathon, you'll likely need a longer training plan. Most runners who qualify for Boston run between 50 and 80 miles a week, which can take anywhere from 10 to 15 hours a week.