The tone of my last post here was misunderstood and deleted. I'll try again with a re-phrase & explaination.
I too get the exact same attitude as your post. I feel I screw up everything I touch, and then I just give up. This battle has raged on all my life.
So many relationships, hands on projects and so on have had to be repaired at some point in my life because I screwed them up. What I have become excellent at is problem solving. I can fix almost anything that's broken.
When I look at my fat I realize it's from me screwing up. I screwed up my diet, screwed up my exercise and became obese.
So, I screwed up and need to fix this. True "fuck ups" know exactly what this feels like, since they have become pros at trying to repair what they have broken. Like you I have found this tool that will assist in my repair. Like any tool it only helps if i use it correctly, you can't drive a nail with a wrench just as you can not lose weight by reading a message board. The nail and wrench are both extremely useful in their elements, but they need your intervention to get there. Same with this board.
Quitting will lead to a painful death, a lifetime of being uncomfortable and the mental abuse of muttering profanity and name calling to yourself. That stream of consciousness would surely be unacceptable here if I were to type it out.
So, to sum it up;
if you are a screw up you have dealt with fixing things you screwed up over the course of your life. time to fix this one. I bet a lot of the negativity in your life melts away with the fat, I know mine sure does.