It is important to understand that weight is entirely a function of input and output. The input is the food you eat and the calories contained therein. The output is your energy output. To lose weight the output needs to be greater than the input. It is that simple. Do not believe any of the diet fads. If you are currently not gaining or losing weight then just burning 300 extra calories per week or eating/drinking 300 calories less per week (2 sodas for example or a small burger) WILL make you lose weight - in this case around 5 pounds of fat per year.
Here's something else most people probably don't know: Fidgeting is good for you. It's considered a nonexercise physical activity, and it's an important way to burn energy. You get more health benefits if, in addition to exercising, you are a more fidgety, more active person the rest of the day. This means gesturing while you're talking, tapping your foot, just moving around.