Science and common observation have proven time and again that a low-sugar, natural, mostly vegetarian diet gives you the most energy, longest life and most mental clarity. Leonardo Da Vinci was a vegetarian, and was known not only for his intelligence, but for his strength. People used to come from miles around to witness his physical demonstrations.
There are obstacles in learning to eat well. It is difficult to eat with less-well informed friends. There are few restaurants that cook with good ingredients. However, if you can eat well for a couple of months, you will feel a transition occur. You will actually seek out the good food by choice. Sugar and salt become less important automatically, and after a while, you will no longer seek them. You will start to feel a confidence when conversing with friends about food, and maybe even help them to eat better and live longer. Soon you will feel a pride in knowing that you have done something good for yourself, and will learn that you can more easily make the major changes you want.