Odds are if you passed the store test, you're ok. Most pre-employment screenings are more for looks than accuracy and they use the same methods and strip tests you can buy in the store. That's because for all of the feigned concern about hiring druggies, as opposed to say, alcoholics, they just don't want to spend the big dough for the GC/MSA tests unless they absolutely have to. That being said, if you are going for a gov job like FBI or cop, you might try to stall (I got the flu, my dog died, my ant farm tipped over, etc) for a couple extra days just to be safe...on the workout thing, don't change that at all. If you increase the workouts you will burn more fat that normal which will cause any stored thc to be released into the blood stream...or so I've heard. And if you're a serious muscle guy, make sure you tell them up front if you are taking any suppliments, as long as they are legal, just to be safe and pre-empt a false positive.