Literally watch what you eat. It may seem apparent that "watching" what you eat for nutrition values is all you really need to watch out for but in reality it is only half of the battle. It is good to eat things that are healthy but even to much of that is a bad thing. Everything but be eaten in rations. When eating, it is a good habit to not only to eat healthy but to literally watch what you eat. When focused on what you are eating, your brain comprehends the size of the food your are digesting and you seem to become "full" faster. When distracted by things such as tv, video games and even reading, our mind wanders from what is important, the food, and is concentrated on the entertainment. This psychological aspect is a major contributor to studies showing that eating in front of the TV is bad. So by actually watching your food you no longer need to rely on just the expansion of your stomach to tell you that your full, but just the mental signals. This alone can help reduce serving sizes allowing for healthier portions and thereby leading to a healthier lifestyle.