@InsanityPolarity while walking is not a bad thing, it isn't really sufficient to lose weight. One would need to walk as quickly as possible. The physics for it is:
Power = force x velocity (where force is mass x accelerstion)
You need power to burn calories. Couple this with controlled intake of calories, and making sure that they are the right type of calories and you will change shape. Adding in elevation helps too, so go up and down hills.
I use the term change shape purposely as I think too many people focus just on weight. I keep track of my waist size. When exercising, you will gain muscle mass, and muscle is heavier than fat for a given volume so you can potentially lose a certain amount of fat, get smaller, but not actually lose weight. If you just concentrate on weight, this can be disheartening when in actual fact, you are achieving your objective.
Also, depending on how much you have to lose, you may not even notice the first stone going. I lost 3 stone a few years ago, and couldn't tell until after the first stone had gone. Take measurements of arm and leg diameters, waist size etc, and track them fortnightly.