If you dont understand this then i dont know ab you but right now this is how im feeling: vbnmnjhgtdwdssthyh7!?!?:K<
and yeah thats about how i feel.

The person who utilize the progression principle will keep adding the difficulty of the exercise that he's doing, while the person who does not, will only stay stagnant.  the person that utilize progression principle, will get a stronger endurance because now his body is conditioned to do harsher routines.{the answer was already on verified)