For the people saying only lard asses fail after 30 days, that is not always the case. It is true that if you are overweight it will take longer in most cases to get clean but I know of plenty of skinny to average weight people who smoked so much for so long it took them 55-65 days to get clean.

FYI:
Aerobic exercise does help your body clear THC but you should stop 3-5 days before the test because those extra metabolites you burn up will end up in the cup. Drinking tons of water days before the test doesn't do anything. Drinking lots of fluids on the day of the test is the dilution method. Saunas and niacin are myths too.