I found that a good way of quitting bad habits (I've never done crack or injected blow), but I have my fair quote of experience under my belt, this way might take a little money but it is as simple as doing it until you become bored out of it, until you realize that nothing good can come out of it, that it is counterproductive, and then you might start a commitment with health and get a better (full?) grip of your doings.
I can't see it working for, lets say, weed, but I can see it working for harder drugs, cigs and alcohol, from first hand experience, I know it does.
Not sure about crack, I look at it as a moneyhole, even worse than cocaine habit as far as money damage, even more damaging than snorted coca,
its merely an ever repeting habit, no symphonies or paintings will come out of it, I believe. So once you have your mind set and a strong will (I know that
logics aren't good enough), you should be good. And if it started from your own will, more power to you.
Good luck on your achievements. If you need to smoke something, go for some weed/hasj, also, an entheogenic journey may help you on strengthen the will and determination. Maybe some mushrooms or cacti can be in order for some inner healing. I can't see any of those doing harm.