I have been heavy all of my life. I have had 3 major yoyo times. Once down to 154, 145, 170. Each time going back up to 200 but never over 220.
I started the BIGGEST loser contest not to win money but to gain self esteem. I have set several short term goals and have met each of them within my time frames.
I think you have to be truely ready in your mind to lose weight. It you are not there mentally you won't get there physically.