The real meaning behind "An apple a day keeps the doctor away"

After posting that myLot discussion on fruits, I have been incorporating fruits into my diet. I like to think I am living healthier lol.:P I am sure many of you would be familiar with the saying, "An apple a day keeps the doctor away". I was just thinking that there may be more than one truth in this statement. Generally, we understand that we are talking about the apple as a beneficial fruit. It contains lots of goodness so eating it makes us healthy and so we will not fall sick and thus we need not visit the doctor. Blah blah. However in my opinion, there is another hidden truth between the lines. This saying also embodies the discipline required to keep us healthy. If someone is sloppy and e.g. cares nothing for eating all the junk food in the world, he is unlikely going to stick to the healthy regime of one apple a day. On the other hand, for someone who is health-conscious, he is unlikely to stop at just apples. He might include more beneficial food items in his diet and he might even oil his engine with exercises. And so, there are really two meanings to this saying. The first is the apple; the second is the discipline. Somewhat like a self-fulfilling prophecy, isn't it? Stay healthy, live long, bask bright. =)