I guess we could find out how many steps he took per lap.
If you divide 18,800 by 8, you'll get 2,350. So 2,350 steps is how many steps he took every lap.
Since every lap he took would be 1/4, or .25, or just a quarter of a mile, and he took 8, that means he walked two miles.
So I guess we could describe his exercise as him walking two miles.