Build to a confident, sustainable 13.1 with steady aerobic (Z2) volume, gentle Z3 introductions, optional short strides, and smart deloads—maximising durability, not drama. Each week blends time-on-feet endurance, one focused quality session, and purposeful recovery so progress stays consistent without burnout. At checkout, pick your metric (Heart Rate, Pace, Power, or RPE) and every workout arrives in that format with clear warm-ups, main sets, cool-downs, plus fuelling cues and race-week guidance. Most athletes choose LIFETIME (Live Updates) for ongoing refinements and fresh cues; NOW (Static) is available if you just want today’s fixed edition.