You should be free to contract cancer in any manner you see fit; you should not be free to force cancer on bystanders. Seriously, you want to smoke? Go smoke, but kindly be polite about it and smoke away from the non-smokers because I'm certainly going to be polite and not tell you how to live your life.
My husband has really bad asthma, and he spent much of his childhood ill because his father didn't really give a damn who he smoked around-those are the types of smokers with whom I have no patience.
As for pot, it's not legal in this country, but should it become legal, I'd ask the same of pot smokers: Be polite! Not everyone wants to get high with you. Actually, if pot is ever legalized, I hope the same restrictions are put on the stuff as alcohol-no minors, no driving because that crap does make some people really spacey (yes, I know there are studies claiming it doesn't affect driving response in some users) and no smoking the stuff in public. Contact highs are a bad thing when you don't know what's happening to you.