If losing weight were like climbing a mountain, a plateau is that bench with the great view.
You can sit down and take a look around.
You could say, "Wow, I've gone far enough... I'm going back down the mountain, this is close enough to the top."
Or you could rest, catch your breath, enjoy the view and say, "Almost there!" and get back up and start heading back up the mountain.
If you're just beginning the climb...
The great thing about having a lot of weight to lose is, in the beginning, you were eating so many extra calories, that you can shave 500 calories per day without noticing it. I know I said that like you already know how to do it -- you may or may not -- I have lots of ideas for how you can do this, and I will share them with you.
You are really strong. You may not realize it, but how many 120 lb people do you know who could pick up a 100 lb weight and carry it with them every where all the time? Not one.
If you have already made it part way up...
The great thing about having lost a lot of weight is you feel lighter and lighter. Moving becomes easier and easier. Life becomes easier and easier.
It still amazes me that I used to have a hard time fitting in a restroom stall, or fitting in an airplane seat, or getting in and out of a car, or navigating my way through a crowded restaurant, or sitting in a booth in a restaurant thinking - I almost don't fit! And then tormenting myself with the "Do you want fries or a salad?" question. That is really an evil set of options. I mean who came up with that one? Clearly someone who wants to sell a lot of potatoes. Oh, and don't get me started on popcorn, "Would you like butter on that?" Without butter, is movie theater popcorn even edible?
If you are "stuck" at a plateau, then this is a reminder to celebrate your ability to maintain the same weight -- a skill you will need to utilize when you reach your goal. You may need to add some intensity to your routine; either in the form of a little less of some of the treats you eat every day, or a little more time or intensity to your workout. I would recommend starting with the eating part of the eat less/move more equation. A lean body is built by what you eat (as in, you are what you eat) and how much you exercise follows as a distant second.
One thing I find when I am at a plateau is I have stopped challenging myself as much as I did in the beginning of my last "climb". I start out of the gate paying a lot of focused attention on what I am eating, drinking, and how much I am exercising. Once a few weeks or months go by, I need a new dose of motivation to urge me up off the bench and back toward my next mini goal.
By breaking my goal up into one week at a time helps a lot.
Trying new things is the most powerful tool you have in your plateau toolkit. If I try to change my habit of drinking whole milk in my coffee, then telling myself I can't have it won't work. But I may say, "What does plain black coffee taste like?" and I might like it. If I don't, no problem I can always add the milk. I happen to be on a little bit of a black coffee kick. I like the tartness that I get that isn't clouded by the milk. Does that mean I will never drink milk in my coffee again? Probably not -- but this may be one more tiny change that will help me break through to see 149, and at 152 that isn't such a long way to go.