That is probably gonna depend on a lot of circusmtances I don't know about you, but I'll do my best to give a generic answer that might be helpful.

In my experience you have to want something better for yourself badly enough that your willpower stands a chance, as well as address whatever problems you were using drugs/alcohol/whatever to deal with in the first place, or its likely you will end up right back where you started.

New positive habits to replace your old bad ones is also pretty important, you'll need new shit to do that you perceive as rewarding (I don't mean video games or other new addictions, I mean real interests/work/hobbies/relationships) to help rewire your brain to look for other ways to meet its needs that are going to make your life better rather than worse