The problem that most people encounter when they attempt to change is that they have the knowledge of how what they are doing is bad for them but their emotions don't match the knowledge.
Is like somehow your emotional system is broken, and instead of helping you survive is sabotaging them. This happened because you are or was abused, and in the process of abuse you end up confused and in emotional pain.
Addiction is an attempt to self medicate yourself for your emotional pain, this is why we have vices and this is why there is a connection between addiction and abuse. Because the purpose of abuse is to make the victim of abuse self sabotage, creating a win lose dynamic. The only instance under which human being feel emotional pain is when they lose something.
The emotional pain gives you the incentive to self sabotage because the main purpose of self sabotage is to cover your emotional pain with pleasure. Because in the process of being abuse you got confused about life now you are lying to yourself, which not only keeps you vulnerable to future abuse but also maintains your self sabotage and emotional pain.
And from this dissonance is impossible to change, you should never address your behavior without taking care of your emotions first. If you have a vice what are you doing is making yourself feel good when you are doing bad and self destructive things to yourself. You lye to yourself because you were lied to by others, and through this form of lying you suppress your negative emotions that should stop your vices. So the way to fix your emotions is through dedicating yourself to being honest with yourself and other people. This at first is going to make you fell kinda stupid when you are going to realize what you are allowing others to do to you and what you are doing with yourself. This is a great thing in a long term because when your emotions match your actions if you are doing something negative is the end of that vice. Because we are design to avoid pain and pursue pleasure you are going to want to feel good and then quitting your vice is going to be a lot easier.
All mental recovery processes start with honesty and end up with ones willingness to fail at acquiring new skills. There is no difference between knowing and doing all evil exist because of ignorance, and there are two types of ignorance.
The first type of ignorance happens when you are deprived of knowledge, a good example of this is smoking until a certain point in time people didn't had the information about how bad smoking is for their body, so from a moral perspective smoking wasn't a vice it was just as bad for you as it always was but just because the knowledge wasn't available you wouldn't had any reasons to stop or associate your disease with smoking. After the science that linked smoking with cancer and heart disease many people had stopped however not everybody.
Ant that is the second form of ignorance or you could call it denial, this people are still ignorant but not because they don't have the knowledge, because they are justifying their bad decisions and suppressing their negative emotions that should make it easy to change their bad behavior. You probably had conversations with smokers, you never see a honest one telling you how much smoking is lowering the quality of it's life or how very little control he has over his habit because if he would do that he wouldn't smoke for to long. Instead they find all kind of justifications involving genetics, family history etc.