Addiction stopped me from quitting. Even sensible people can find 'good' reasons to continue with an addiction they know is harmful. If they try to stop, they can come up with reasons to start again. They are lying to themselves but rationalise the lies in their mind.
Quitting is hard. Your body will ache, your head will ache, you will lack energy, you will feel like crap, you will get twitchy and OBSESSED with whatever you are quitting until it becomes unbearable.
You tell yourself you will have just one and then you'll feel better. You can NEVER have just one. You quit or you don't.
You decide to cut down instead of quitting. It is another lie. You cut down a little for day or two and then revert back to your old habit.
Many years ago, someone on the radio said 'try not to smoke for ONE hour'. After the hour, they asked how everyone was feeling and challenged them to try for another hour. After that I was desperate, twitching and in urgent need of a cigarette. I decided that was not good and accepted I was addicted to rolled up sticks of vegetation that I put in my mouth and set light to, even though I couldn't afford them and even though it was harming me. How stupid is that????
I decided not to have another cigarette until I was so desperate I was willing to concede I had been beaten by a white roll of vegetation. It was hell but my ego was stronger back then so I would not accept being beaten. That was in 1983. So far, I have not smoked but, even now, I know how easy it would be to let my addiction take over again.
I had to treat my addiction as though it were an alien living inside me who lied to me and made me hurt and who tried to trick me into smoking again. The first week is the hardest. If you can stay smoke free for a week and then NEVER allow yourself excuses for going back to smoking/weed, it gets easier.
The money I saved made a huge difference to my life, giving me the means to buy some real quality audio equipment and a better car. I have never regretted the struggle to give up. Now I am free.