As pointed out by many others, what you probably lack is discipline more than common sense, in your own definition, simply because you are aware that your actions are not good for your body.
Common sense is basically pattern recognition, something we acquire as we grow up, and something, i strongly believe, has great potential to mature in any given person.
Ability to solve puzzles would be a good measure of common-sense, this, i think, is not very controversial. Puzzles are like encryption, easier one way than the other. Once you know what you want to test in a person, you can usually device a question in a tricky way that serves your purpose. You can add and remove information as you shape the question, and when you are satisfied with it, your test is created. To solve it, is a whole different ball game, because, often, you do not know what you are being tested at. But, solve enough puzzles, and you begin seeing patterns to them.
Common sense, in a way, is different from genius, although they are both quite similar, imo. Common sense is culturally restricted. For example, it was common sense that Sun revolved around the Earth, because people saw that happen everyday. To say otherwise, would probably be considered as an indication of lack thereof. Genius, imo, is born in the instant one takes the effort to verify common-sense and comes up with something new, that is contrary to belief / useful / beautiful. I do not mean that if your result confirms the previously held belief, you cannot be a genius, but simply, that it wouldn't be recognized, or worse still, be condemned. And the reason i think common sense and genius are similar is that, till a breakthrough is made, genius may manifest as plain common-sense.
If you look at things carefully, you might find that things of very different kind seem to follow similar patterns, or that one thing can be described in terms of another. For example, i tend to think of my state of mind in terms of attractor states. Once i'm in a particular attractor state, i'm comfortable and it goes on well for a long period of time, and generally, it takes external influences to draw me out of it (although boredom and a tendency to try something new work their ways from time to time), and when i become ill-disciplined and unable to concentrate on important things, i imagine myself in another attractor state, or in the stage of transition between two different states. This helps me take further goal oriented action, which i simply was incapable of doing before i applied this method of thinking.
Another differentiation, i think at this point, should be made between intelligence and success, because imo, it's a vastly misunderstood concept. Intelligence is the ability to process information in a way that is logically consistent. It indicates nothing as to your motivation to carry about a result of your own process. That is, you can make the most fool proof plan for success, but still fail, simply because you did not follow it.
Success on the other hand, is process dependent. You might be unable to see solutions to complex patterns, but as long as you are good at following well established guidelines for doing something, you are likely to succeed without requirement of a high amounts of intellect, or, even understanding the point of those guidelines at all.
I hope i could clear some of your doubts
