I got into this a little last summer, but I've finally come to the conclusion that running with music whose beats per minute match your normal pace is an incredible way to run.  I kind of stumbled into it by accident when I noticed my pace matched a few of my favorite songs.  Alternatively, I would assume it's fairly trivial to measure one's pace by simply counting the number of steps taken in a certain amount of time and dividing the former by the latter.  Once you have that magic number, it's just a matter of finding music with that BPM or a multiple of it.  I find that not only do I run faster, but I completely zone out and feel awesome (although that could be a function of how music affects me personally).  It's almost like instead of running while listening to music, I'm listening to music while also running.  Very therapeutic. #sports