Exercising

Exercise is the most important aspects of controlling your weight. If you exercise heavily or work hard you will require more food, conversely if you have a sedentary lifestyle you will require less food. These amounts referred to more or less of the amount of food required for your RDA / height.

Starting

Starting to exercise his hard, if you start to exercising today for 20 minutes and continue this every day it will take two or three weeks before he have any desire to continue exercising after this time you will start to want to exercise. Don't worry if you can't do 20 minutes to start with, time yourself doing as much as you can but pushing yourself to do more each day.

Walking

You only have to look at any crowd of people walking to see that overweight people generally walk slowly while those who walk faster are generally fitter and less overweight. Walking fast is a good way to exercise where as walking slowly will do little to contribute to your exercising.

Lifestyle

If you have a sedentary lifestyle and are overweight you will have to change your lifestyle attempting to reduce your weight with out exercise would be very difficult if not impossible due to your body's requirements for food, any dropping of nutrients that is significantly below the required RDA slows any weight loss due to insufficient nutrition ( starving response).