I'm training for my second marathon and have some help from a friend whom is an experienced marathoner. I've always run too fast (for my amateur ability) and wondered why I always got hurt, why my legs were always sore, and why I didn't make substantial gains after training. I've been doing most of my miles now around a 10 mm and notice how much stronger I feel especially when I do my tempo/interval/stride work once a week (sometimes more). My weekly mileage has gradually increased from about 25 to 40 over the course of the last 4 or 5 weeks and expect it to get to the mid 50s by the end of the summer before my marathon at the end of September. I've seen many of the folks posting on RA talking about more easy miles with targeted workouts of intervals/tempo etc and it has really held true for me too. I really look forward to the days where I can push it a little on my speed days. I'm trying to get better about consistently staying within the plan and when I don't I get little aches and pains (like my recent Achilles issue) then need to back off. Anyway, if you do some digging on the RA forums you can get some great info. Good luck.