quit cold turkey is the best. ur problem in the rest room is a habit. u need to break the habit,u can wake-up early,change the timings. donot get excited and light-up the cigarette. u need to relax for a few moments , u can listen to music on ur phone or talk to someone. one day break and continue for the next 21 days and ur habit is gone.
u can also rub or keep massaging the anatomical snuff-box below the thumb area.

Hi friend,
Welcome to Health Care Magic

There is modern medicine for the smoking disease.

If you do not want a drug, still you can be helped - like any other addiction.
De-addiction specialist - usually psychiatrists - can do this.
Social support - friend, family, colleagues - is important.
You have the motivation / you only need to execute it - stop it immediately, completely and permanently
Avoid the company of smokers and environment.

Take care
Wishing speedy recovery
God bless
Good luck