You can re-condition your beliefs and habits by accessing your sub-conscious mind
We are self-reflective. We can actually choose what we put into our brain and what habits we would like to have. So you see, you really are the driver of your destiny. You can change any belief or create any habit you want and make it a part of your sub-conscious... If you know how.
How long does it take to change a bad-eating habit and replace it with a good one?
NASA conducted an experiment on its astronaut trainees. It took the astronauts and fitted them with glasses that flipped their field of vision 180 degrees, quite literally everything was upside down. They had to wear the glasses 24hrs a day, 7 days a week. The trainees struggled along seeing things flipped and feeling disoriented. On the 26th day one of the trainees found himself able to see normally again and the others also found that they were seeing normal by the 30th day. Their brains had corrected for the changed external environment (glasses) by re-wiring some of the nerves or neural pathways. We call the development of new neural tissue or networks - neuroplasticity.
That tells us that it will take approximately 30 days to create new habits! Not by just eating differently but by an actual daily process that deals with your mindset. It is not as simple as replacing one for another, you need to actively condition the mind to change the programs that are creating your habits. As you recall, your eating habits are a product of a lot of different learned "bad" programs. It is these programs that the re-conditioning process will change by creating new programs and strengthening them through neuroplasticity.
You will re-condition to the point that anytime you are hungry or whenever you are going to exercise, your new programs will run or play and make the choice of going to the gym or eating healthy completely effortless. No need for willpower and no presence of an internal battle. Can you see how this is VERY different from just forcing yourself to follow a diet or exercise program?!?!