What are ways to keep myself from overeating?

Eat! But eat smart.: It's not just number of calories but also composition of those calories. Carbohydrates tend to get burned up quickest, although you can choose healthier low glycemic carbs w/lots of fiber. Protein is more filling & sticks around longer & delays hunger. Choose lean meats, fish, chicken, even beans. Don't forget healthy fats & oils like fish & vegetable. Both will also help fill you up.