Now being serious, while hard, i do think human being can achieve a high lv of control of its mind, thus managing to accept/believe/do what they consciously want.
But obviously its not a casual effort but a quite large set of mental practices so you can induce it to believe what you want to believe.
First thing to do is actually want something. Second is looking by yourself what mental tricks/tactics you can use. I do know some but im sure its more effective if you look for some and actually believes some tactic can work.
Well, but i fully agree thats always easier to say something than to live that thing. The only thing i feel like an addiction to me is drinking coke i guess. I did had some intervals when i could stop drinking it but substituting for other sweet drinks or even drink more water than needed.
Though, as i wanted to stop drinking coke because i wanted to lose some fat, i ended coming back to coke because i could reduce carbs from other sources so i did achieve my goal despite not stopping drinking coke.
BUT as i used to drink 1L+ per day, nowaday i can limit it to one or two cups at most. So thats another tactic, reducing first to mitigate the side effects.