I smoke marijuana.
I have been smoking on and off for the past 10 years, and it has been a fairly significant part of my life. I do not smoke cigarettes.
First, let me say that I am a legal medical marijuana patient, and a huge advocate for legalizing medical marijuana. I have done a very good amount of research and feel completely confident saying that marijuana is much safer than alcohol, and can be extremely beneficial for many people.
Certainly, most people don't even realize why marijuana is illegal. I'd like to give a bit of history, which will perhaps shed some perspective:
Marijuana has been used medicinally and recreationally for centuries, going back to the Chinese Emporer Shen-nung in 2737 B.C. (almost 5,000 years ago). It has been used throughout modern history, even into the 1930's. It was available over-the-counter until 1937. The plant which grows marijuana is a hemp plant. Hemp has a number of uses- from paper to clothing to even (oil replacing) fuel.
Around the 1920's-1930's (roaring twenties into the great depression), The Hearst Corporation was rising in power. Hearst was a newspaper tyrant, logging company owner and major WOOD-based paper advocate. Hearst began replacing hemp paper (a quickly renewable and more earth-friendly resource) with wood paper in order to satisfy his own interest with his logging business. In order to build his business empire, he had to come up with a way to decrease hemp's popularity.
This is when the smear campaign against marijuana began. Eventually, what happened is that Hearst basically cuts a deal with the U.S. government, and they begin to spread his anti-marijuana propoganda without medical proof. Hearst basically created the idea that marijuana was harmful only for his own personal gain. He was able to convince people of the evils of the plant without any real, unbiased, medical evidence.
If you'd like to read a bit more detail, this site is a good reference.
Obviously, knowing this alone isn't enough to convince someone that marijuana is safe. Want to hear some more truths about it?
Nobody has EVER died from a marijuana overdose; not one recorded death has been attributed to marijuana. People die from overdosing on Tylenol. Studies show that it would require ONE THOUSAND times the regular dose to die from marijuana. In 2001, there were 331 alcohol overdose deaths and 0 marijuana overdose deaths. Source: U.S. Centers for Disease Control (CDC). Here's a chart comparing marijuana to other drugs:

From Saferchoice.org
The biggest risk involved in marijuana use is the possible lung damage from smoking the drug. Fortunately, there are many other ways the drug can be administered, including through foods (cookies, brownies, candies), or vaporizers (devices which extract the THC for you, causing no damage to the person inhaling). Regardless of possible lung damage, there has NEVER been a case of lung cancer documented in a cannibis-only smoker. In fact, recent studies find NO cancer-marijuana connection.
They have linked cancer to such common products as deodorant. People still use possibly cancer-causing deodorant, it's still legal and FDA approved.
If you want to read more about marijuana history and facts, SaferChoice.org is a good place to start.
I would not engage in an 'illegal' behavior without adequately researching it. I think I have proven that I didn't just choose to use cannibis without being certain of the risks. Now that I have briefly explained the history and health aspects of marijuana, I'd like to explain why I choose to use it. I use the drug both medically and recreationally. Judge if you'd like, but I urge you to do some research of your own before you pass judgement.
Medically, marijuana is legal in Denver, and has been for nearly 10 years. My perscription was written by a medical doctor. My medical marijuana card was issued by the Colorado Department of Public Health and Environment. This drug can be perscribed to assist so many serious conditions, including: Cancer, Glaucoma, HIV/AIDS, mussel spasms, seisures, severe pain/nausea, IBS/IBD/Crohns/Colitis, Muscular spasticity, and many more.
I have had my condition for 16 years. It is a chronic condition that doesn't "go away", and most times, patients are on strong and invasive medicines for their entire lives. At age 11, I tried every invasive medicine and treatment including extremely harsh steroids. Eventually, I stumbled upon Eastern medicine (accupuncture and chiropractics). Just months short of a life-altering surgery, I fell into remission with strict accupuncture treatments.
I consider myself infinitely lucky that I didn't have to have the surgery, and have been able to keep myself in remission for nearly 14 years now. I will occassionally experience symptoms again, which is part of what inspired me to pursue medical marijuana. I had already used marijuana recreationally on and off since I was 16 when I finally got my medical card last year. Honestly, it makes me feel SO much better, and it also helps my neck and back, where I most likely suffer from Arthritis. On top of those, it also helps to quell my anxiety, which had gotten progressively worse in the past 5-7 years.
Really, I can't even put into words what this drug has done for me medically.
Recreationally... well, basically anti-pot commercials are ridiculous to me. When I use marijuana, I don't just sit on the couch like a big lump, ignoring my friends and responsibilities. I function as a normal human being, minus the high anxiety and stress I'm usually dealing with. I run errands, have a job, get work done, clean my apartment... I'm well-spoken, not uneducated or poor. I don't commit crimes. I'm not a meth addict, nor do I abuse other illegal drugs. Basically, what society wants you to believe about marijuana simply isn't true.
I'm ME. The same "me" I've been for 27 years. Maybe even a better "me".