SpartanII, all the posts here give great advice on letting go your addiction, just pick pieces and bits from each one and you're ready to go!
One very important point, just as others mentioned, is to choose your friends wisely, ditch the ones that keep telling you to do one more hit, one more joint, one more "trouble"... those are not friends, they are just pawns. And keep those that respect your opinion and won't do anything in front of you and won't talk of how good it is/was, in this way, you are actually helping each other
I can talk about the marijuana addiction, I was addicted to it for 13 or 14 years, heavy use, I mean, I would smoke a joint before anything that I would do, and I had no job for awhile, so even more time to smoke it, I would wake up and either take breakfast or smoke one, after breakfast and before reading the email and check for news, another joint, if the high was subsiding, one more joint down the throat, before going out to do whatever, another joint, and it was like this till sleep time, basicly, anytime the high was subsiding I would get another joint just to keep the high going, so I was literally high all day.
How to stop it?
The route I took was first and foremost, leave the group of friends that do it.
Secondly, I started diminishing the amount of joints per day. And this, in my case, was the "holy grail"! Before smoking one, I would ask myself "why am I gonna smoke this one now?" and when the awnser was simply "To get high", then I started rejecting it. And one by one, day after day, the amount I would smoke per day was lesser and lesser till I was smoking around 2 per day, just by night and alone, it was 1 to "chill" from the day, and 1 to help sleep.
With just these 2 per day, you really notice a good amount of energy during the day, you simply got more energy to do whatever needs do be done.
After this I ditched the one before sleep because I couldn't recall any dreams, it was all blank. But still I noticed I would not recall them very good either, so I ditched the one to "chill" and my dreams became all lively and the recall memory started functioning again!
This method of diminishing the amount per day didn't bring any withdrawl symptoms on me. In contrast with a couple attempts I made on just leaving it "cold", I would get irritated at everything.
There's a nice documentary about marijuana and the THC effects on your brain and how it all works, if you wanna watch it, here's the name: National Geographic - Drugged: High on Marijuana.
It explains very well why there are withdrawl symptoms, basicly, the THC is present in every human, it's what makes us get calmer, and since we're taking THC on our own, the brain stops producing it; and when we stop smoking it all abruptly, the brain doesn't immediately produce the amount of THC as it used to, it has to adapt.
After stopping smoking, the amount of energy you get is amazing, you just have to choose how to take the best use of it

Be it running, jogging, doing yoga, meditation, turning to bonsai trees as 7baz did, it's your choice, choose something you enjoy and you're ready to go!
Best of luck SpartanII!
