Exercise is a must! Keep your metabolism up though exercise and resistance training. Why? Because we lose 10lbs of muscle a year. When we exercise, we also have this great post-exercise period called "EPOC." Exercise Post Oxygen Consumption = more calories burned. The magnitude of the EPOC can change with different types of training. Weight training and circuit training where you have 40-70 seconds under tension per set will rev up the metabolism. More tension your body is under, the higher the metabolic response.
On days that you don't feel like working out, if you just start moving your body and eventually you will gain enough momentum to complete a workout. Make it an absolutely mandatory that you will do something everyday, even if it is simply going for a long walk or doing 100 pushups in the park but that you will do something. Remember that a 100 calories burned a day is 2800 calories burned a month, 33,600 calories burned a year which is 10 pounds of body fat.