For me, it was realizing (after about 50 of the 70 or so pounds lost so far) that it's not about losing weight, but increasing my own intrinsic awesomeness, and being satisfied knowing that whatever positive changes I make to my lifestyle increases my own intrinsic awesomeness. Weight loss, health, feeling physically better on a day to day basis, possibly looking more attractive to the ladies, being comfortable in my own skin, these are (great) side effects to the whole intrinsic awesomeness thing. Same thing goes for reading books. I'll never need the knowledge of Antarctic exploration in my life, but reading a book about it increases my intrinsic awesomeness, it makes me better as a person, and as side effects I might have a better appreciation of life, of what these men went through to increase their own intrinsic awesomeness, and my brain might increase in speed by having read and processed the information. It's not awesome to waddle into a fast food place and stuff fried foods and soda into my sweating body with all the other fat people. It is awesome to eat a salad at home and go for a run around the apartment complex with my dog, and not die from exhaustion. Taking the time and putting forth the effort to search out the deeper, harder to find, and therefore more meaningful pleasures (eating salad, reading about Antarctica, running with dog), rather than accepting and being happy with the easiest pleasures that have no depth or meaning(fast food, crap TV), stuff that has just been provided for me.
Coming off like a motivational speaker here, but I think it might be helpful to some people to hear that it's not strictly about weight loss, that if you do this right, you will become a new person, not just be the same old you with a smaller pants size. It's helped me to approach this(my health, and life) from a more spiritual, basic angle. You'll get off the fast food, crap TV, for-profit medical industry treadmill and actually work hard and accomplish something in your life. So eat a salad, read a book about Antarctica(it's fascinating), and go for a run with a dog.
I also love big salads.
PS Please try to read some humor into this post, though I am serious about it. I realize this approach is not for everyone, but it has helped me, and it might help someone else. I'm back after something like a three year hiatus. I've spent the intervening years figuring a lot of this stuff out. Mostly it was a process of turning from exterior motivations(which, for me, ultimately fail), and turning to interior ones. Basically I had to learn to do this for myself, and not to try to live up to expectations.