My grandfather has smoked since he was 14, and he is now 74. He doesn't have lung cancer though, never has. Does that mean smoking isn't bad? No, it still is horrible for you. And so is smoking weed. The chemical in it deteriorates the brain, makes your memory worse or deteriorates it, and when you are high, it's like being drunk. You lose motion control to an extent, you lose mechanical abilities, reaction time is not as quick. Saying weed has no negative affects, like half the idiots in this thread, are ignoring facts.