My teenage daughter used to hog chocolates. Every night she used to take a pledge that it would be the last bar she is consuming and there would be 'NO CHOCOLATES' from tomorrow. If Guiness Book has a record for the maximum broken pledge , then she would get it. She does not eat a single chocolate now! The change happened last year , when she got her monthly quota of a popular branded chocolate and opened one after her dinner. She found worms wriggling out of the bar which she has bitten already. She spat the same and scrubbed her mouth several times . Beleive me , she did not touch chocolates after that. Sh says that whenever she sees chocolate , she gets reminded of THAT DAY.
So if you need to quit anything , you need to associate a 'VERY UNPLEASANT' emotion to it. It works.