The various forms of monitoring are generally useful (and genuinely useful) techniques for altering problem behaviors. However, while monitoring your behavior does tend to have a mild inhibitory effect (e.g., you generally do things you're ashamed of less often when you're paying attention to them), in most cases it is not powerful enough by itself to get you to stop doing those behaviors entirely. Self-monitoring tells you how often you are behaving, but it doesn't necessarily help you alter the various rewards and punishers you are experiencing that cause you to behave that way in the first place. Until you can get those rewards and punishers under control (or better control your reaction to them), you are unlikely to stop your problem behavior.
An important point needs to be made here. Minor behavioral problems can be handled with willpower alone, or with a combination of willpower, appropriate planning and the aid of supportive friends and associates, but some other behavioral problems are just too powerful and overwhelming to handle alone. Addictive behaviors fall into this class. Addictive behaviors are maintained by a combination of strong rewards and punishments that are very hard to overcome without outside assistance. Drug intoxication produces a "high" state characterized by feelings of euphoria, relaxation, power, or insight provide an intense reward for continuing to use, while painful withdrawal and craving symptoms punish any addicts who try to get clean. Though addicts might know rationally what they need to do, their behavior will typically continue anyway unless they get outside assistance, because the conditions that maintain their behavior are generally too strong for their mere will to overcome.
In general, anyone who wants to change a deeply entrenched habit needs to appreciate that mere willpower alone will generally not be enough. If you think about it, even a little pain is enough to keep people from doing things they know are good for them, like exercising regularly, or eating less. When willpower meets punishing or rewarding stimuli that promote an old unwanted behavior, generally willpower will melt away and the old behavior will continue. You need more than willpower to overcome resistance to behavior change. You need to have a solid plan based on learning theory principles, and you need to have your basic needs taken care of before you stand a good chance. You can increase your odds enormously by enlisting others' help and support in executing your change plan.
We can distinguish between two types of problem behaviors or habits: those designed to get us away from things we fear, and those designed to get us closer to things we crave. Phobias and other anxiety problems are examples of the former sort of habit motivated by avoidance of punishment, and addictions are examples of the latter sort of habit based (at least initially) on approach towards reward. Different sorts of methods are useful for each habit type.