It takes 2 weeks to start a habit and one to break it. For years I was in your position where, I thought, I'd shed half my weight if I went for a long walk or didn't eat that chocolate cake. To keep my motivation, I set a long-term goal that was beyond numbers on a scale and so far this year I've lost heaps of weight (see my sig for exact numbers).
My advice, think about that reason which made you want to lose weight in the first place. Write it down on post-its and place them around the house, make it your computer wallpaper, put it as an alarm on your phone, write it down every day, guilt yourself with it when you are making excuses to get out of exercising..... Whatever it takes, especially if it means that much to you.
(Guilt, reminders on my phone from MyDietPal (I think that's what it was called) and inspiring quote wallpapers got me started!)
I hope this wasn't too over-the-top or intense for you! I'm recovering from a long, tiring run and my bright-side is slowly returning as I recover lol