I put "long" in quotation marks because one mile isn't really long to somebody in shape, but it is to me. Would I be better off running a mile to a mile and a half at a time (along with a stretch, 3-5 minute walking warm-up at 4mph, and the same amount of time for a cooldown) or running at a faster pace for say, half a mile, then walking for half a mile, running another half a mile, etc. until I tire out? I've heard conflicting opinions about this. What are you guys' thoughts?