It is not at all a simple task to reverse the habits cultivated over umpteenth lifetimes. It is next to impossible without gaining a good knowledge of the Dhamma and putting it to practice diligently. Then, and only then you are going to have any success in thwarting the mind’s ingrained habits. The personality view is the hardest of them all. If you could begin altering your habits, one day in the years to come you will be very thankful for getting into a path that made the impossible possible. Now it will feel like drug withdrawal of an addict when quitting the bad habits.
We can alter our habits because they too are impermanent. Consciousness too is impermanent and constantly changing. Thus, all these aggregates are constantly changing and impermanent. They are processes, not things. They are dynamic, not static. This knowledge will help us to see personal experiences in terms of processes, in terms of impersonal functions rather than in terms of a self and what affects a self.
You’re learning to use the tools that Buddhism offers to sort out your own mind. First the tools help you look at the habits, the things the mind is doing. Then goodness will come, not from any innate goodness in the mind, but from a keen sense of the dangers of the unskillful habits already there, and the benefits of the skillful habits that one can develop in their place. Once we have this understanding, we can overcome ingrained habits. This is why the Buddha said that heedfulness is the root of all skillfulness.
In psychotherapy, to root out ingrained tendencies in the mind one may trace things back to what you did as a child. The teachings of the Buddha instead gets you to focus on looking at your habits right now, as they keep coming back again and again and again. The Dhamma will inform you as to what is virtue, and what is not; what is blameworthy, and what is not; what should be made a habit of, and what should not. This will get you to civilize your eating habits by learning to wean yourself from your passion for the junk food of sights, sounds, smells, etc., and look instead for good food within.
Unlearning some old habits is not easy. After a while complacency sets in. Complacency is a form of sloth/torpor. Complacency can be said as lethargy in the body (sloth) and drowsiness in the mind (torpor). It is when the mind is not sleeping, but not awake either. So be aware of this twilight zone, where nothing of use is achieved. Buddha advises us to be aware of this enemy in life that would stop you from succeeding in life. So we have to make a habit of getting up early every day, being energetic. Energy arises when one has a clear-cut direction. One knows exactly where one is going and keeps at it. This is one to keep Mara’s armies at bay.
Also check Cetana Sutta 3 - S 12.40 to find out how we form our personal habits.