I played the PC version for almost 9 years. In those 9 years I reckon I tried to quit about half a dozen times. It would really only last a couple of months at most before I'd return. I think if you explicitly go ''I'm going to quit on this specific date of dd/mm/yyyy for good'' then you'll fail, like myself and everyone else has done.
I've been off graal for well over a year now and that's because I never really made that conscious decision to quit. Other things came along that I decided to focus my life on.