It is generally not easy to overcome anything like addiction. Addiction requires a very strong determinati and energy.
So, people struggle to overcome drugs addiction, because it requires just more than determination, but the grace of God.
Without the grace of God, you will not be able to stop addiction completely.
And I also think that, sometimes one can develop a practice of staying away from people who are addicted to those things. And becoming conscious of yourself and determination.
Even in all these things it is the powerful brace of God that can pull you off drug addiction. Because it is generally not easy. I have seen people whom drugs has dealt with them so badly, I mean so badly.
It becomes difficult for them to leave, so difficult. That's the very reason why one needs to engage God in this to be able to survive. Amen!!