Writing is one of the most cognitively demanding tasks students face yet too often they're expected to produce extended essays before they've got the hang of writing sentences. Inspired by the Couch to 5k running app, Writing Fitness rethinks the way we develop students' writing, offering a structured, cumulative model to build fluency, precision, and confidence over time.Dismantling the flawed assumption that writing is a generic skill that students can simply "pick up" through exposure or repetition, this book proposes a model of explicit instruction, deliberate practice, and curriculum alignment, offering a tightly structured approach to writing instruction that breaks down complex skills into teachable steps. Grounded in cognitive science, grammar instruction, and classroom-tested routines, chapters include:Exploring the principles of gapless instruction, cognitive load, and schema buildingExplaining how to break essays down into teachable, repeatable sentence typesPractical guidance on everything from teaching thesis statements to embedding evidence and analysing structureSentence-level drills and the Deconstructed EssayCreative writing, addressed through constraint-based Slow Writing exercises that develop style through structureA reframing of assessment as an opportunity for feedback, planning, and consolidation, rather than merely performanceIdeal for English teachers at Key Stage 3 and beyond, this book offers a practical roadmap for improving writing outcomes - especially for disadvantaged students. With its blend of theory and detailed exemplification, Writing Fitness equips teachers to deliver writing instruction that is rigorous, inclusive, and sustainable across the curriculum.