You can't win over your bad habit by self control, you will have to self resist from that environment which act as a cue and lead you to repeat the same bad habit. Look you can't use your willpower in the long run your will power can work upto 1 or 2 days but somewhere you get in the temptation and you fall under the prey. 

your dopamine plays a vital role in your habits when researcher experimented the mice with increase level of dopamine every time they poke their nose into the box then mice suddenly started poking 800 times per hour in order to complete there craving and when you consider a human being we are also not so different from mice, a slot machine player averagely rotate wheels nearly 600 to 700 times in order to win the price. similary your habit is dopamine driven loop. when you take drugs or eat oily foods, browsing social apps like instagram and Facebook. These are all associated with release of dopamine. You can also relate dopamine level release in your daily life like eating, drinking, talking, intercourse are all associated with the dopamine value. 

but now after scientists years of studying came to know that dopamine plays a vital role in many many neurological things which includes motivation and punishment, dislike and your various voluntary movement. earlier scientist use to think that dopamine is related to pleasure only. But now dopamine is not only relased during pleasure but also when you give advance thought to take action in preparation for something that you think will happen. when you will see a gambler addict person their dopamine level spike just before they order a bet and there is no dopamine spike after bet is placed and cocaine addicted persons dopamine level increases when they see that powder not after consuming the powder so whenever you predict that some opurtunity which you will meet give you high reward so that is the point your level of dopamine spike in anticipation of that opportunity so in this way whenever your dopamine level increase you start acting. so now if you closely see it is the anticipation of reward not the attainment of it that lead us to the action and there is very intresting fact that reward system gets activated in the same manner when you anticipate the same reward. 

Thank you.