What's up bro, when I was going through it I only ran maybe no more than 10 miles a week. when it comes to running information it's not too bad there are slow groups and fast groups, just go with the slow groups. To be honest, even though I came into OCS pretty fit I tend to run with the slow group because it's just easier on your body in the long run, and OCS PT isn't meant to make you in good shape it's just there to make you miserable. Unless you are out of shape you really don't have much to worry about. But maybe I'm pretty biased because pre-OCS and post OCS I'm an avid gym rat. Hope your shins are conditioned for running plenty of folks broke their shins/legs somehow and got disqualified. if you're not used to either jump roping or running you should start bro.