I think the best thing we could all do is take it in really, really small baby steps. For me what has worked best is taking it really slow, and like Chris said, being really gentle with myself. You have to make mini goals and keep them until they are habits (but good ones at that). For me I started with eating a healthy breakfast in the morning. I have been doing that for about a month now, so I have started on the next step... back to the gym. I have to really force myself to take it slow there. But I won't work on the next step until I get going to the gym every day. And it doesn't have to be the gym... just anything generally to keep yourself healthy, such as breakie in the morning, drinking lots of water during the day, adding more fruits and veggies to your diet, getting out for a walk every day, stretching every morning, etc.
To me the most sure-fire way to fail is to try to do it all at once. But going slow for me is difficult as I'm an instant gratification person. But already the benefits I am seeing from slowly altering my lifestyle make it worth it. And that's the thing - I don't think in terms of a diet. I think in terms of having a healthy lifestyle. To me that's the key to success. I want to reach my goal weight but I want to do it in a healthy way and have it be something that I can maintain throughout my life. Just take it one small step and one day at a time.
Cheers,
Dietrie