Developing healthy eating habits isn't as confusing or as restrictive as many people imagine. The first principle of a healthy diet is simply to eat a wide variety of foods. This is important because different foods make different nutritional contributions.
Secondly, fruits, vegetables, grains, and legumes - foods high in complex carbohydrates, fiber, vitamins, and minerals, low in fat, and free of cholesterol - should make up the bulk of the calories you consume. The rest should come from low-fat dairy products, lean meat and poultry, and fish.
You should also try to maintain a balance between calorie intake and calorie expenditure - that is, don't eat more food than your body can utilise. Otherwise, you will gain weight. The more active you are, therefore, the more you can eat and still maintain this balance.
Following these three basic steps doesn't mean that you have to give up your favourite foods. As long as your overall diet is balanced and rich in nutrients and fiber, there is nothing wrong with an occasional cheeseburger. Just be sure to limit how frequently you eat such foods, and try to eat small portions of them.
You can also view healthy eating as an opportunity to expand your range of choices by trying foods - especially vegetables, whole grains, or fruits - that you don't normally eat. A healthy diet doesn't have to mean eating foods that are bland or unappealing.