It's going to take a lot of patience and a lot of will power for you to do this. You're ready to comit to a plan so find one that will work for you and make it your own and go for it.
This is what I'm doing right now. I portion-size my meals. That means for each meal I eat a much smaller amount than I used to, i.e., instead of a full dinner plate I now use a smaller breakfast plate (be careful of bowls) to serve my meals on.
I also make sure I eat breakfast everyday, this ensures that I won't be so hungry during the day that I crave and feast on anything in sight! I also eat at least five times per day and have gotten to the point where my stomach is now used to the quantity I take in that if I overdo it I am uncomfortable for hours.
While doing this portion sizing, I now make it a point to eat more vegetables and fruit at each serving. There are times when I don't eat enough fruits, I've noticed that, so I'm going to remedy that because fruits are a necessary part of your diet. (not weight loss diet but your food intake in general)
I started out very slowly to exercise by walking for a 15 mins at first at a steady pace. Then I gradually increased the duration and the speed at which I walk as I felt more fit and energized.
I also started to workout. I do aerobics, jump rope, and I use a threadmill and eliptical machines at the gym. I also do free weights and the weight machines on odd days. If you don't have access to the gym or machines, then doing your own routine at home is good too. That's actually how I started before going to the gym. Doing sit ups, and other aerobic activities is fine.
So just find something that will work for you that you won't get tired of or bored with and stick with it. It's hard but it will get you going once you start. If you ever need help or encouragement of anykind let me know. It helps to have a buddy! I created a new blog called Wellness-Serenity.joeuser where I can share my thoughts and experience on my quest for a fitter life. And I also share any information I learn on fitness and health. It's an open blog where you can go to share your thoughts too if you wish.
One caution, you should get a health check up by your doctor to make sure you're ok for starting any program. You could even go to a gym and get a stress test so that you can know what level you're at. Good luck!