When I was a young man, I did my share plus about 100 other peoples share. Lots of stories, but I can say one thing for sure, it didn't make me violent, nor did I every wake up with a hangover and said "I'm never going to smoke that again".
Martial Arts change all that in my early 30's. The hard core of judo players that I became close to were mostly cops and troopers. I didn't want to let my team mates down by being caught with it. I've never done it since then, would like to try it if it were legal, but I have too much to lose by trying it now.
I get bad hangovers from alcohol, still drink a glass or two on occasion, but I'm kind of glad I get hangovers so easy as it keeps me away from something that is bad for your body, worse than marijuana will ever be. I have read (and it could be wrong) There is less problems with smoking marijuana than cigarettes because of all the chemicals they use to process and make cigarettes taste better. I'm guessing most people that smoke weed wouldn't smoke nearly as much as a cigarette smoker.
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Don't believe everything you read on the internet- George Washington.