Just stop!
But what helped me: often smoking is part of a daily routine or ritual, so mix up your routine. Take up a new hobby or take the bus instead of the car. Go for a walk after lunch. Giving up smoking is a big change, so don’t be afraid to make big changes. Get new clothes. Make new friends. You have discarded your old identity as a smoker. Still smoking? Doesn’t matter! You already want to stop - you’re becoming that person already.
And don’t be so hard on yourself if you have a smoke now and then. Be conscious of what situation or routine triggered the reflex, and change it in future. If you have a smoke every few days or weeks, don’t sweat it, you’ve broken addiction as far as I’m concerned!
Slogging through FFXIII here. It’s super linear and repetitive, but just what I need right now.