Hhmmm...it seems as though rather than lack of motivation you may actualy have some self worth/esteem issues. I know. I have them too, and it was the same with me for years. I was just hiding behind lazy. I lost 35 pounds and was happy with myself for the first time in my life and I let it slip back on. It took me a long time to find my voice to do this all again, but I did. And you will too. That is all that matters. Don't be overwhelmed by all the dieting resources available to you. Just find something that you think you will like and stick to it. If and when it dosen't work, then you canre evaluate. I used overwhelmed as an excuse for a long time also as well.
You will notice that a lot of people on here have replaced neagtive, self hatred with positive self talk. This REALLY really helps your attitude, perspective and self esteem.
Positive affirmation is very good also, little phrases you repeat to yourself on a daily basis that retrain your thinking process.
http://www.more-selfesteem.com/affirmations.htm
TRY SOME!!
And just remember this is a journey, when you see it like that it becomes a whole lot lighter
Best of luck,
Anna