A lot of self-defense schools emphasize getting away from the threat. Often times, that is good advice (unless you are in a teen slasher movie). But when fleeing is an option, if you do it prematurely, you are setting yourself up for failure. Every battle in human history that ended in slaughter started out because one side broke and ran...and the other side ran them down. So if you decide to run, do it on your terms. That is, either you know you can outdistance your opponent safely, or because you have imparted enough injuries to ensure he won't chase you.