Our subconscious tries to keep us safe
The reason we do many of the counter-productive or even self-destructive things we do is because at some level these actions at one time made us feel better. They comforted us and kept us from emotional or physical pain. The word "comfort food" couldn't be more descriptive, accurate, - and harmful! When people drink, gamble, or face other vices for the first time it makes them feel good temporarily. Only, our subconsious does not recognize that those are temporary fixes and so when stress or pain come back our subconscious drives us to seek that which made us feel better. And so the cycle repeats and we find ourselves engaging self-destructive behavior even after we consciously decided not to!
That's why reprogramming our subconscious into learning different ways to keep us safe and happy is so crucial. If we can retrain our subconscious into positive methods of dealing with stress, pain, boredom, etc. we immediately see success in overcoming those dangerous old habits. Our subconsious wants us to be safe, healthy, and happy. Our subconsious actively desires what is best for us. We can harness that powerful sense of self-preservation to help us reach our goals.