This plan is written for an experienced runner who's looking to break 4 hrs for the marathon or improve their time below 4 hrs towards 3 hrs 45mins.A 4:00 hour marathon is approximately 9:00 per mile. To break 4:00, you should eventually be capable of a sub-1:50 half-marathon (8:20 per mile) and sub-50:00 10K (8:00 per mile). Right now, you should be running at least 20 miles per week, and be able to run for an hour non-stop.