who is a boy and looking for a girl has to be older than 12 and younger than 16 looking for a boy friend and im in 8th grade

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)