You have to first want
You must want to change your habits, want to lose some weight, want to give up your evening snacking before your will comes into play. Once you want a thing badly enough, you will do whatever it takes.
If you think you want something (to make a change in your eating habits perhaps), but then find it difficult to follow-through with your plans, most likely you simply want your current reality (your current habits and patterns) more than you want your goals (less weight, better health, etc.)
Want Power Before Will Power
I can hear you all the way over here, telling me I'm wrong: "No, that's not right! I want this more than anything, I just don't have any willpower!" Round and round you go, but the truth is, you will get what you really want. Think back, has there ever been a time when you really wanted something? A certain piece of clothing, a certain house, car, job, spouse? Hum... Yes, we go after what we want, if we really want to acquire or achieve it we do. Nothings going to fall in your lap, you've got to go get what you want.
What's Going on?
Put another way, you may want to avoid the pain (breaking old habits, avoiding some favorite foods, simply not overeating...) more than you want to gain the pleasure (losing some weight, gaining new habits, eating favorite foods in moderation ...)
Since losing weight takes time, from weeks to months to years, it's easy to fall off the path. It's always easier to get back into our old habits of eating, eating, and more eating. There's always more food. Unless you are too poor to purchase it, there's plenty food in America - in fact, too much food, and so it becomes even more necessary to keep the longer-term goals in mind.
How do you keep the longer-term goals in mind, when the short-term food is staring you in the face? What about all the treats offered, what about the commercials, the billboards, the signs everywhere that say EAT?
Wanting, in fact, is the "W", the first step in the W.H.A.C.K approach. See it in the free e-book, Changing Beliefs, Your First Step to Permanent Weight Loss.
Think back to when you last really wanted something. Wanted it more than anything, had to have it, would do just about anything to get it. To want is a mighty powerful motivator, but surprisingly we aren't all motivated by what we want. Some of us are motivated by avoiding what we don't want.
What is your Motivation Strategy?
Motivation comes in two (or more) flavors. You can be motivated towards something (what you'll gain) or you can be motivated away from something (what you'll lose). This desiring to avoid can be confusing. I'm saying you must want something, and you're thinking, but I don't want to be fat. I can't think about my future, only what I don't want. Here is what's going on:
If you are motivated by what you'll gain you find it easy to look ahead and see your future shapely body, you'll see people around you with admiring glances, you'll hear their compliments, you'll smell the good food and feel good knowing you can eat enough to be satisfied, and then say you're full. You've had enough, thank you. You'll be in control of your life. You'll want what you visualize more than anything, and you'll do whatever it takes to get it. If asked what movie to go see, they'll have a few ideas, and tell you why.
If you are motivated by what you'll lose you'll focus on what you want to avoid. For example, you want to avoid dying, you want to avoid being too heavy to enjoy playing with the kids, you want to avoid gasping for breath when you climb a flight of stairs. You want to avoid the embarrassment, the humiliation of other people's remarks and rude glances. You don't want any of that anymore, and you don't want it to the extent that you'll do whatever it takes to avoid these things. If you ask them what they want for dinner, they'll tell you they don't want Chinese, or pizza. It can be difficult to get someone motivated this way to actually say what they do want!
Knowing your motivation strategy makes it easier to find methods that support your preferred strategy. If you are motivated toward, you may enjoy cutting our pictures of people in great shape with similar body types to yours. Find models wearing clothes that would look good on you, pictures of swimming pools, holiday places you'd enjoy; the types of things that go into a dream board.
If you motivated away, then make a list of what you want to avoid and elaborate on that list. Why don't you want these things? The more detailed you are, the more likely you'll truly do what it takes to avoid them.
Hopefully these ideas will get you thinking, and much about making changes in our lives comes down to thinking it through. Realizing what we really want can get us past the hurdles of what we already have. To affect change isn't necessarily comfortable, until you've worked at it for awhile, and then suddenly your changed behavior has become your new behavior and the effort is over.