That ‘Personal Rule’ of Lee’s had been brought into existence for the sake of better his mind and body through training.
The rule was this:
once Lee decided he was going to do something, then even if it looked like the world was going to crumble and disappear tomorrow,
he would still see it through to the end. It was a principle he stuck to with overwhelming devotion.
Until he could think of a nice present besides dumbbells, Lee would run endlessly if he had to.
By the way, Lee wasn’t counting just running around the village border as ‘one run’.