1. Doing a certain action twenty to forty times in succession forms a habit "as easy to follow as not"--
2. If you persist "further in the habit without lapses, it will become second nature, quite difficult to shake off"--
3. Continue the habit "through a course of years, and the habit has the force of ten natures-- you cannot break it without doing real violence to yourself."
(Taken from CM Series Vol. 1 p. 110)
That last step reminds me of a caller I heard on Dave Ramsey's talk show once. This man and his wife had lived a life of financial wisdom, worked steadily, saved and denied themselves luxuries, bought a home, put kids through college, saved for retirement-- all without incurring debt. So why was he calling Dave? Because he had a much higher income now that he was retired (all that saving paid off) and he just couldn't change from being frugal to splurging once in awhile! Years of habit are very hard to break.
What habits do you hope will be difficult-to-impossible for you or your kids to break thirty or forty years from now?