So far, it hasn't been a struggle for me at all. (Knock wood)
I'd smoked since 1984, except for a period of about 6 years. Once I started with my V2s, I didn't have the urge to light up at all. I still had an ash bucket outside my back door, and when I would step outside to go to the convenience store or check the mail, I would catch a whiff and be totally put off from smoking.
I did find a half-smoked Marlboro Light (I called 'em refries) that I did light up since I couldn't bear to waste something that was so important for my entire adult life...and it was gawdawful.
I'm one of the lucky ones, I s'pose. I haven't looked back, even under stress. I just keep thinking back to that smell, and trying that last smoke, and I put it out of my mind.