Mentally and intelligentally you know you should not smoke because it is bad for your health, but you physical dependance on the addictive ingredients in tobacco is what keeps you from being able to quit so easily.
I know smoking is bad for you but it is really hard to quit because nicottene is very addicting stuff. I have tried to quit many times and i have also failed many times I think the best way to do it is pick a date get your kit and stick to it.