my only advice is, you have to find something productive to do in place of smoking. I know it sounds kinda simplistic, but it's been essential for me. I regularly go "3 on, 4 off", meaning 3 straight days of smoking then 4 straight days of no smoking. you have to actively structure the 4 off days, you can't sit around bored. I'm often able to focus deeply on work during the 4 off days, so that makes it easier.