"Acceptable losses" can mean so many different things in different situations. To a military commander it can mean the number of casualties in a battle. To a college student it can mean the number of hours of sleep lost while cramming for an important exam. To me, it means doing whatever it takes to learn a new skill or pass a belt testing in TKD.
I'll never forget how important it is do do a hammerfist properly when trying to break a board because of a bruised wrist received by doing it wrong. Or how important it is to hold even a foam sword properly because of straining the same wrist while trying to block my opponent's strike. I can be pretty sure that I won't make the same mistake. At least not in the same way...lol.
My husband and I have a goal of eventually opening our own TaeKwonDo school. To get there, there will be a lot of time spent in training, sore muscles and joints, and more than likely some bruises along the way. Those are what I call acceptable losses, because its all worth it when I see the kids in class doing so well at testings and tournaments, and learning skills that will help them in life.