Well, to tell ya the truth, I dont do it by miles or anything, I just run between 25-30 minutes, and throw some sprinting in there too. Its that interval training some people told me to do on here. Jog, then sprint, jog, then sprint, over and over. It works well for me. I think it prepares me for lasting in the ring and being explosive, you know, getting in there and throwing those combinations and getting out.