This plan will prepare you to run a 26.2-mile race by running four or five days a week with weekend runs building to a peak of three hours. It’s useful to have experience at shorter distances before you make this leap. A few successful half marathons will give you the experience and confidence to move to the full marathon. How will you know when you are ready? If you’ve followed my half marathon plan without injury, you should be good to go, and many of the workouts will be familiar. Otherwise, have a look at the first four-week block of this plan. If the first week looks totally doable, or even easier or shorter than what you’ve been doing, you’re probably ready. If it makes you flinch, start with the half marathon and target the full distance next year.