A very important step towards becoming fit is keeping track. Most people aren't aware of the little things they forgive themselves for and later forget. With money, you will increase your spending if you have an increase of income in the future. Likewise, you will increase your eating if you upcoming physical activities. Keeping track is one way to curb your eating.
Have a PDA? It's great for taking small notes to keep track what you've been eating. A small pad of paper or a set of index cards also works nicely. You can sit down later on and calculate your total calorie intake along side your intake of carbohydrates, fats, and proteins. After a few weeks of keeping track, you'll have found out which foods that you like are better for you.
The reason this works is that you have a specific outline of the things you have eaten and the consequences of the food you chose to eat. You can also write down the exercises you have done and see which ones give the best results. A written record puts things into a relative perspective. One of my friends took pictures of everything he ate over the course of a month. When he reviewed it later, he realized some key weaknesses (namely that he overeats on spaghetti) and was able to adjust his diet to overcome his cravings.