There are times when you are an ex-smoker when you will find yourself thinking of how nice it would be to have a cigarette. There are times when you were a smoker when you would find yourself wanting to quit. It is likely that the longer you go without smoking there will be fewer frequency of these times and the duration of these thoughts will usually become shorter when they do occur.
The same concept doesn't normally hold true for the alternative side. The longer you smoke and the more you recognize about the dangers of smoking and the more restrictive the society becomes around you regarding smoking--the more frequently you would find yourself wishing that you would quit.
So again, neither side is perfect but the ex-smoking side gets better and better while the problems you face as a continuing smoker would get progressively worse over time. Not to mention that your health would be continually negatively impacted by the interim smoking and eventually smoking could rob you of your life. Neither side is perfect but the ex-smoking side is far preferable and you can keep that side as long as you simply stick to your commitment to never take another puff!
Edited October 1, 2012 to add in new video version of this string: