What makes you think he's bragging when he says he's doing just mileage?. Seems to me like he's just telling people who are interested what he's doing. But you think doing "just mileage" isn't enough which is to say you think you know more about running than a guy who has performances that only the tiniest handful of us can even come close to doing. That's arrogant stupidity, "Just mileage" worked very well for guys like Ron Clarke and Mark Nenow, both of whom settled on that approach after doing other things earlier in their careers.