Start at the beginning, work to the middle, then head for the end.
I get asked that question a lot, and wanted to share some of my thoughts on losing a lot of weight.
My very best advice is to do the following:
1.) Be totally rigorously honest
with your food and exercise log. On food err on the side of logging more than you ate and on exercise err on the side of the lowest amount of calories burned.
2.) Start out logging what you eat now and then work your way down to your lose 1 pound a week number by making smart food choices. You should not be eating less, but eating better if you make good food choices.
3.) Exercise, exercise, exercise. Just do it. Find the time, make the time, invent the time if you have to. Consistency is the key. Make a plan and follow it. Make it so that you would no more start your day without some exercise than you would skip brushing your teeth.
4.) Use the forum. Lots of good people here willing to help and share knowledge with you. Everyone is so encouraging and supportive.
5.) There are many paths to fitness. Find what works for you! It is not the same for everyone. If something is not working for you - change it, find what will work for you. Find what you are willing to make part of your lifestyle and run with it.
Lastly - you have to believe that you are willing to make a change in your lifestyle and that it is something that is good for you. It is something that you want. It is not willpower, but willingness to change that lets us break out of old habits that are unhealthy for us and move in a new healthy direction.
I wish you the very best and would be happy to help anyway I can.