I'm a former smoker and binge drinker. Both of those were a hundred times easier to give up for me than food. I had lost substantial amounts a few times in my life, right along with having substantial gains. However, I did pretty well at losing about 100 pounds and maintaining for several years, but hit a brick wall in late 2011 when several family crisis hit all at once and I returned to comfort food. And before I knew it I was pregnant for the first time, but lost the baby just a few days shy of completing the first trimester.

I was absolutely miserable. It was the first major gain I'd had since 2003 or so, my emotions were a wreck, and I was having so much trouble just physically getting around. I allowed myself some time to mourn as I pondered how to get my life and health back.
Once I decided I'd had enough I already knew what I needed to do; what I'd lacked all along was sticking to something long enough. This time, I set an absolute starting date a few weeks out. I gave myself those few weeks to ease into healthier habits while ditching the unhealthy ones with baby steps.
That absolute date was March 5th of last year. I made a commitment to myself that once I reached that date, I would do my best with a healthier lifestyle and that I could not give up on it, no matter what. And on that date I went full-force, starting with logging my food in a day planner. I picked a pretty one and bought a pretty pen to go with it. I made sure every decision was one I could be proud to put in writing. I focused getting through one day at a time, one meal at a time. I turned the day planner/journal into a game when I was having a rough go of it, putting star stickers next to completed days. I looked into ways I could improve my nutrition and exercise, and with it I drowned out those negative thoughts. I focused on the habits instead of the results. I kept pressing forward even through the days I wanted to throw tantrums and cry, even through the weeks I stayed perfectly on plan yet showed a gain on the scale. Whenever I stumbled I forgave myself and got right back on plan. I knew my habits were solid and that I just had to stay on track and trust in the process.
Ever since starting that planner, I've lost an average of one pound per week. Which doesn't sound like much, but by stubbornly sticking to this I've lost 56 pounds and am currently at the lowest weight I've ever been at as an adult. The planner has been an extremely valuable tool for me, and has even become something I look forward to filling out with my healthy choices.
Maybe a journal/planner/book would help you out as well? You can follow any plan you like, and it's possible that such a tool would motivate you to stick with the lifestyle of your choice.
