Unlearning habits requires persistence and perseverance and above all Grace. The effort should be primarily in two directions.
First is to forcibly stop the wrong habit by steady application of the will as well as diverting the mind each time the tendency recurs. Staying busy helps a lot in this process. Often simply witnessing the habit without actually indulging in it is the best way.
Secondly one should reform new healthy habits which contradict the old one.
Thus for example if it is a habit of drinking tea one can replace it with lemon water rather than stopping it.
Above all surrender to the Grace does the rest.
Affectionately,
Alok Da
