Which activity should be part of a long-term plan to positively affect your health?
A. Having a skin exam only after you turn 65
B. Using lead paint in your house
C. Avoiding secondhand smoke
D. Drinking water from all sources

C
Explanation

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)