First thing, hi, and welcome to these boards!
I've myself read both the "Thin For Life" and Dr Phil's book (7 keys to weight loss), and they've really helped me tons when it came to understand certain mechanisms of my overeating. I can only recommend them (and to be honest, Dr Phil's one was part of my "click"; even "only a book" can help in this!). The Dr Phil one can really help in isolating, understanding and correcting bad eating patterns, even though some of his suggestions don't work for everyone (for instance: when I'm alone at home, I can't eat without reading, else I'm too bored and don't enjoy my food; if it doesn't work, don't force it

). The Thin For Life will give you examples and tips & tricks from people who've maintained important weight losses through years.
Another thing I've understood so far is that the weight loss shouldn't be envisioned as a "what can I do to lose the weight now, I'll worry about the maintenance later on" problem, but as a "what will be good for me now and for the rest of my life". Eating plans can be a good way to give you a right start, but as you can't rely on them for years, it's good to experiment, try to control what you eat, identify your risky foods, etc. You may of course have to behave more drastically at first, after all, there IS a difference between losing and maintaining; the key is simply to not let way to all the negative talk or to illusory thoughts, such as "this is too hard, I'll never be able to have pleasure in eating anymore", or "when I'm thin I can eat 'like before' again". It's both about getting used to better, healthier eating habits, and learning moderation so that we can still allow ourselves "treats" here and there, *but* without overeating each time.
I'm not sure of what your exact problems are, but from what you mentioned in your post, it could be simply that indeed, "sticking to a plan for long" isn't the good solution for you (too discouraging, too hard, too deprivating...). Perhaps what would work best for you would be to initiate simple and gradual changes, such as starting with skim milk instead of whole, putting less fat in cooking, allowing yourself treats but in limited quantities (small packages instead of family-sized ones, even if it's more expensive comparatively), and slowly increasing exercise as well (this I can only recommend; I know that some say you can lose without exercising, however, it really helps tons, will make the slimming down results faster, and will also make you feel better, which is part, after all, of the "healthier lifestyle" thing).
In any case, I hope that the "click" will occur for you soon, and that you can find a way that suits you to lose the weight permanently.
