IMO, changing workouts, or the idea of frequent changes comes from boredom. After 3 months of a near daily routine, some people get bored and complacent. They get lazy with their lifts, and are more just going through the motions, versus actually getting a good session in. So they change, and as they change the body responds differently. So of course, the change is the reason. Not really.. the reason is the mental change that one must take on when running something new. A new challenge brings new dedication, and therefore no more complacency. And boom, results, "just start pouring in"..
When in fact, all it takes is a single, simple will to do one thing.. as mention by Fazc. Get Strong.
Mt Snow, VT - May 5, 2012 - Completed!
...i remain, he who remains to be...