Setting small attainable goals is important in your success. If you have a lot of weight to lose sometimes thinking of the whole picture can be a bit overwhelming. For example if you need to lose 100 lbs to be in a healthy range, focusing on that can make you feel like your goal is so far away and you may get discouraged and give up. That is why I feel it is important to set smaller goals, like going down one jean size or walking or jogging a mile without stopping or focusing on 10 lbs at a time. That way you experience success when you reach those mini goals and you are motivated to go on and reach the next goal.
When pushing through and trying to reach your goals, please don't think shows like The Biggest Loser, offer results that are typical or easily attainable in a short period of time. It is important that you know with proper nutrition and exercise losing 1/2 - 2 pounds a week is more typical then what you see on that show (understand that if you have more weight to lose you are going to lose it at a quicker rate, it is those last 5-10 lbs that go slower and harder). Those contestants work out hours and hours every day (I have read 8 hours before but not sure if that is accurate) and they don't have distractions and responsibilities such as work and family and they don't have a lot of the temptations like fast food or junk food lying around the house that you may face on a daily basis. Those things make a huge difference! I have had clients come to me thinking they should be able to lose it as fast as the contestants on that show and they get disappointed and frustrated when they don't. Slow and steady wins the race! I find the most successful people don't rush it. Gradually make adjustments in your daily living that add up and help you achieve success.
For your final weight goal try not to have an exact number on the scale be your goal, a range is better. So many people get stuck on hitting a number they were once at or have always wanted to be at and that can set you up for disappointment. As you begin working out you gain muscle mass and that is a good thing. Increasing your muscle mass increases your metabolism and makes you burn more calories even at rest BUT when you increase your muscle mass the number on the scale may not drop down as low as you want BUT that is OK, you will look better b/c you are losing fat and gaining muscle therefor looking healthier and more fit! A lb of muscle and a lb of fat of course both weight the same (a lb. he he) but a lb of musle takes up less space then a lb of fat so you may look tighter and smaller but weigh the same or more then you did when you didn't have the muscle and had fat instead BUT please believe it is better to have that extra weight from the increased muscle mass then to be unhealthy with the extra fat that you had before!
Believe in yourself, work hard and don't give up. I believe in you!