Been smoking for 4 years, now it's more than 2 years since I quit. What worked for me might work for you:

Make a list of Cons and Cons for smoking(could be weed also):

Cons could be :

• Expensive
• Smell on clothes (or hands) ...

On the othe hand, the Pros should be listed like this(stay with me, even though it might seem cringe a lil bit LOL):

*Breathing- Once I'll quit smoking my breathing will become lighter and healthier.

*Smelling - Once I'll smoke I will enjoy the good smell of food, perfumes (and otger good smelling stuff)

*Eating - Once I'll quit smoking, I'll enjoy eating with the need of smoking, my enjoyment will increase...

The trick is that every Pro could be listed as con and vice versa. But keep telling yourself the benefits you'll earn once you quit smoking. There are tons of reasons you should stop smoking, you need to find yours.

Every now and then, read this list and remember why you started to resist to this smoking impulse, and you will stop, have faith.