Well since noone posted yet. I have not done this personally but I heard this way is ineffective. Drinking that much water for a long period of time is going to work. Excercise is ok but I think what you are looking for is to dilute the THC. In order to do that drink like 8-10 cups of water about an hour before your test. Don't use the start or end of your stream in the cup. That is pretty much exactly what I have read and the person said it worked.