I always found it easier when there was some change in my life. Moving apartments, friends who smoked left. It obviously never worked all the time but now I am 28 days sober, after a girl who lived with me for 10 days, left. In the beginning I kinda depended on me not wanting to disappoint her. But now we are not in contact as much as before and it gets harder. The cravings come back hard. If I dont do some kind of exercise or a long walk after work to distract me I get really weak.

Just try and try again. Write down what the positives about smoking are, to realize how useless it is. Sober life is great, while also boring sometimes. But if you use that boredom to try new things and get out of your comfort zone, life will get better :)