My Mum quit smoking in 1994.
It wasn't the first time that she'd quit, but it was her last time.
Her first few attempts to stop, though sincere in effort, lacked the certainty that she would follow through with it. With that attitude, naturally, when the temptation came along for her to get back into them, she took it up once again.
She took a different approach in 1994.
She picked the date that she was going to stop, and made a promise to herself that it would be the last time she ever did it. Then when the date arrived, she threw out anything that associated her to being a smoker: cigarettes, ashtrays, everything.
She burnt her bridges.
Sometimes we just need to get so absolutely certain on what the outcome we want is, and then give ourselves every opportunity to follow through.
It helped her.
It might help you too.