Our brain has a primitive emotional side which just wants what feels good and doesn't think rationally about anything else. Our brain also has a rational side which thinks rationally and knows drugs are bad. There is an endless struggle between our primitive emotional side that wants drugs, and our rational side which knows drugs are bad. Our brain is constantly making decisions. What to do? Who will win?
To successfully overcome addiction we need to strengthen the rational part of our brain so it can overpower the more primitive emotional desire for drugs.
When you activate a thought, it strengthens and reinforces that thought. Think a thought over and over and eventually that thought becomes strong. We are here to exercise our brain, to strengthen our desire to stay clean and sober by simply thinking that thought. Remember, thinking a thought, strengthens and reinforces that thought.
A muscle doesn't instantly become strong by lifting a weight once. You have to do it over and over, day after day. Do this mental exercise over and over, day after day: breakfast, lunch, and dinner; when you wake up, and when you go to bed. Keep that idea strong enough to always overpower the primitive brain's desire to relapse. This is one of the goals of support groups. They're a ritual designed to reinforce your desire to stay clean.
Note that initially you may find yourself still using drugs. This is because the emotional side is still stronger than the rational side. Do not get discouraged. Just keep exercising that thought that you want to stay clean and sober. If you keep at it, eventually a day will come when the scale tips in favor of your rational side. The rational side will become strong enough to win the struggle, and you’ll be able to stay clean and sober from then on.
From then on you will always need to exercise that rational thought to keep it strong. When you stop exercising a muscle, the muscle slowly withers and decreases in strength over time. If you stop activating that thought, eventually your resolve will weaken and you’ll be vulnerable to relapse.