When you are tracking your calories, plan out what you are going to eat for the day but then at the end, leave some calories designated as "extra". This will help in relieving some of the guilt when you want an extra couple crackers before you run out the door, or whatever.
Think of your calorie counting as a budget, if you plan what you are going to spend your money on, your are less likely to splurge. Budget for the most important, responsible things first, then leave a little left over for splurging. Food is the same, plan nutrion first, then leave room for treats.