Hi and welcome to 3FC. You've just stepped into a great place for advice, encouragement and support.
For me, there was no mystery as to how I made it up to 287 lbs. I ate waaaaay too much food and the wrong ones. I ate irresponsibly and without putting much thought into it. I didn't adhere to any kind of healthy eating plan. I ate whatever I wanted, when I wanted (& I wanted a LOT) - without putting much thought into what I was doing to myself and how it would affect me longterm. And though I ate whatever I wanted, when I wanted - I wasn't happy. Sure the food TASTED good, but than the food was over (quite quickly) - and so was the good. Not so good in the end.
As far as us keeping you motivated, that I'm afraid is something you'll have to muster or your own. We're definitely here to support you and help you out, but the motivation has to come from you. Besides we often say around here that motivation is not ENOUGH to get the job done. Motivation is great in getting one STARTED. But to see it through, all the way to goal, that requires work, dedication, perseverance, determination, grit, thought, effort and COMMITMENT. That commitment is what gives you that stick-to-it-ness that is needed. That commitment is what will force you to cut up that salad instead of grabbing that muffin or calling up for a pizza. That commitment is what will get you off the couch to take a walk. That commitment is what will help you to pass up on the cakes and chocolates. That commitment to do this NO MATTER WHAT is essential. So I urge you to make an ironclad commitment to do this - once and for all and permanently so that it won't matter if you feel motivated or not.
My starting weight was 287 lbs. Don't have my exact numbers in front of me, but I believe I lost about 18 lbs that first month. I was heavier than you (& probably shorter), so the weight most likely WILL come off faster initially. But I urge you to not compare yourself to others. We're all different. I also wouldn't focus *so* much on the scale. It's the behaviors.
Focus on the behaviors. Focus on your plan, customizing it and tweaking it as need be. Focus on eating well and exercising. Focus on always having the right foods on hand. Focus on finding healthy, lower calorie foods to eat and fall in love with. Focus on strategies and tips to get you through the *rough* times. Focus on alternatives to stress eating. Focus on making good choices. Focus on getting great healthy habits in place. Focus on that and the scale will go down. Each and every excess pound on you, can come OFF of you - as long as you continue these good behaviors. So try and focus on THAT.
My plan? I'm a calorie counter. It's built in accountability and instant portion control - something I desperately needed (still do). I count calories and combine that with eating whole foods. Helps to keep me full and satisfied and keeps the cravings at bay. In the beginning I completely banned sugar, pasta, rice, flour and the such. I had a REAL hard time stopping with those foods once I got started - my solution - don't start. It was waaaaay easier for me to say know to the first bite than the second and third, and fourth...
My plan also includes exercise, which I started out doing slowly and increased as I went along. Walk Away the Pounds DVDs by Leslie Sansone are a great way to get you going. A simple inexpensive resistance band can also do wonders.
What plan will you be following?
I'm so glad you're here and I look forward to hearing of your progress.