Well it's all around self control. If you try to stay away from drugs in the first place then you won't get addicted... However, if you're in the case where you can't stop and you know you're addicted there a plethora of activities you can do to help yourself. Maybe getting addicted to something not as harmful such as reading, video games or TV shows. Physical activity also helps and it has helped a lot of addicts. Try picking up a hobby such as playing an instrument. You can always still go to therapy and work out your problems with a therapist or group therapy.