How can I lose 100 pounds in 6 months?

Well, eat healthy and go ahead and do 3 hours of work at the gym. Go for a walk or even a bike ride. Its much cheaper. Oh and set your goal for longer than six months. I mean you should average about 10lbs a month. In 6 months you will be back where you were. If you go for too much too fast you will likely fail and that will end up killing your self esteem all over again.