lets see here:
the only negative impact of marijuana i could see, is that you'll become a habitual user, as in you'll get in a pattern of using. however, this isn't necessarily a bad thing, marijuana is much safer than: crack, heroin, meth, prescription medications, McDonalds (fast food), hospitals (staff infections..), cliff diving, driving, and pretty much anything the media tells you to consume...
plus, coffee, cigarettes, fast food, soda, sodium, and even candy, is WAY MORE ADDICTIVE than marijuana, and lacking those will cause more damage to the body than marijuana will...
and withdraws for marijuana, don't occur until about 1 month after your last consumption, even then they are extremely minor, the withdrawals are actually so minor that you may not even notice them... consequently, you may notice lack of sleep, or restlessness, marijuana is commonly associated with restless leg syndrome (RLS).
so here is a list of the worst problems with marijuana and the solutions.
GOING TO JAIL - this will kinda fuck a lot of shit up, best thing to do is, if your a smoker, BE A SMOKER, don't get caught up in other peoples bullshit, and STAY THE FUCK OUT OF THE TRAP SCENE (if you don't know what the trap is, good, don't learn about it)
Becoming a worthless drain on society - ok so marijuana can make you sleepy, happy, and hungry right?, but if you can't keep your job, schooling, or relationships, maybe marijuana isn't for you. And you should wake the fuck up.
really though, just be responsible & reasonable about it, and be informed about your local environment (ie. job/school requirements or testing).
and dont let the high come from the weed, let it come from the life (or whats behind the weed)
ps: the whole nuerological impairment is a bunch of shit,
marijuana is plant, not a drug. however, its kinda like KFC, if you keep eating it, you'll get fuckin fat, so moderation is always key, and not for just pot, but for everything
the quote below is crapeeeeeeey!!
CORRELATION DOES NOT EQUAL CAUSATION, this basic concept is a HUGE DEAL in the world of Psychology.
I'd put it off until your an adult, not because you can't make decisions for yourself, but because I think the risk of neurological impairment at a later stage outweighs any benefit of marijuana for adolescents. It should be noted that causation hasn't been 'proven' but even still, a strong correlation should be enough to abstain as the implications could be devastating should the correlation foreshadow proven causation at a later date.
http://www.health.harvard.edu/blog/...or-later-schizophrenia-psychosis-201103071676
http://www.schizophrenia.com/prevention/streetdrugs.html