Thanks, friends, for your comments so far. I dont usually follow up to respond. But in this case, I just want to clarify that my opinion can basically be summed up as train for what youre about to do. To me, its not about having to *race* the marathon or having to run the whole thing at a specific  pace. I definitely agree that you can run a marathon and walk bits of it. I often walk through water stops so I get enough hydration, which ends up helping me keep my pace. I dont want you to think that I have some standard about what pace counts as running or racing. You can race a marathon at an 11-minute mile if youre running against a clock.