Anything in life worth doing can not be achieved without the determination and perseverance. During a process of dieting, setting your goals is very important. When you look at things honestly and objectively, you will notice that most of the things you have accomplished in life have been accomplished, not only because you have a goal, but also because you had a clearly planned the process and have a clear design to achieve this goal. That being said, why goal setting is so important when it comes to dieting?
Firstly, it is difficult to achieve a goal if it is not clearly defined. There are moments in life where it is almost impossible to tell whether you are successful or not. Identifying your goals before you start dieting in particular eliminates this possibility.
Secondly, having a clear goal of dieting gives you a way to measure from which you can judge your process. This is important so you know when you need to change your goals to get there. Remember, your goal should be achieved and you must also be willing to set new goals if the former did not work for you.
If you set goals that are beyond your reach, frustration will be your diet buddy until you reach the point where you give up everything. To avoid this you need to set realistic goals.

When setting your goals, you must be realistic. The fact that you aim high may seem admirable, but to set unattainable goals can be cons-productive. If you expect instant results, you will become discouraged and soon it will be too easy to give up. Set high standards, but you must put it in place gradually. Each week you will notice an improvement and a little time you go where you want to be.
Rather than setting a total target of 40 or 60 pounds, start with a specific goal, such as losing 10 pounds in a month. Then you can expand the goal next month until you reach your overall goal. The goal of ten pounds sounds simple and feasible; but forty pounds sounds like an insurmountable obstacle.