Totally forgot to mention this last night: JTM told me he thought I was probably running too fast after he followed me while wearing his fancy Garmin GPS (swear he SHOWERS with that thing on: "Hey I logged .000001 of a mile this morning AND deep conditioned my hair!). Says to slow waaaaay down. And I was reading a bit about lactic acid, and the anaerobic threshold, and thought it might be time to stop sneaking peeks at the other treadmills and just do my own thing - not worrying if my running pace is slower than the next person's walking pace.
And sure enough: it was lactic acid all along - not asthma - not a bum ticker - just the big bonk coming way too soon! So when I slow down to 4.1, or 4.2 mph, I can pretty much avoid it all together. Now only plain old ordinary fatigue is what slows me down. I ran for ten, yes TEN minutes without stopping the other day. Woot!