Wow, ToughRNMudder326! I'm exhausted thinking of all those races - during nursing school or not. :-)
I have a good treadmill and typically read/study while I run, but I attribute my ability to stay injury-free the last several months (I have been prone to overuse injuries in the past) to being able to run 90% of that high mileage outside, so being on the treadmill so much for training was a concern. Listening to lectures while I run is a great idea, so I will definitely give that a shot, so I can still get the best of both worlds of study time and outside running. And it can help with the guilt of leaving my family for a few hours on Saturday mornings for my long runs since I'm basically studying during that time. Half marathons crossed my mind (they are my favorite distance, actually) but since I've already done a handful, I was hoping to get that full one in.