You break a bad habit by taking the following steps:
First, focus on how painful the bad habit is in your life or to those you love. Focus on the pain, discomfort, embarrassment, etc. it brings you. Allow yourself to experience these feelings and let them become REAL to you. Do this only until you have achieved a state where your desire to rid yourself of the habit moves from the head level to the heart (much deeper) level.
Second, visualize this habit removed from your life. See and hear the results you will achieve in your life when this habit is broken. Allow yourself to FEEL how you will feel when this habit is broken - empowered, proud, strong, noble, or whatever it is you know you will experience. Focus on this successful outcome and continue to "daydream" about this outcome every day, instead of focusing on the bad habit. Resist any temptation to "pull" you back by giving the habit place in your thoughts, words, or actions.
Third, enlist the help of supportive people ONLY. Tell them what your are doing and ask for their support. Then, make yourself accountable to them. Be honest with yourself and them. Don't hide or tell fibs about where you are in the process at any given time.
Finally, do this continually and the result you want will become a reality, and you will be living the result you desire.