You're fine. THC is stored in fat cells. By exercising every day, you burn those fat cells which accellerates the rate at which it is expelled from your body. That, plus it was only two hits.
The main factors of weed staying in your body are: Amount of body fat, how often you burn body fat, and how much you smoked.
Two hits would be out of most people's system in a matter of 2-3 days. Some heavy users can be detected in piss tests 6 months later. If you haven't smoked recently and only took 2 hits, I'd bet a lot of money you'll be clean.
At home test can never hurt though. Also, drink a good amount of water before you go in. It will dilute your piss, which makes the concentration of THC seem less (You only test positive if the concentration of THC is high enough).
Worst case with dilution is they say your piss is diluted and you have to go back and take another test, giving you longer to get rid of it.
Wow that was a lot of pretty unnecessary typing. Oops.
[This message has been edited by Disarmer (edited 5/10/2012 2:09p).]