Erin -- I was at about 300 pounds when I started. Like you, I had made promises to myself MANY times about losing but never got started. Then, for a while I just gave up and resigned myself to being fat forever.
I think I finally realized that someday my weight was going to seriously affect my lifestyle.
Let me rephrase that... my weight WAS seriously affecting my lifestyle, but I realized it was only going to get more severe, especially if I kept gaining.
I was finally able to COMMIT to a different lifestyle, even though I started slowly, first by just portion control. When food came along that I didn't think I should eat right then, I asked myself "Is this WORTH it?" And I have been able to pass up many foods since then by answering "NO" to that question -- though there are times I do indulge.
I don't think it's always about motivation, per se, but about sticking to a commitment we make ourselves and a promise for a healthier lifestyle.
I want you to know that you CAN do this if you want to! But you have to find a plan that works for YOU!
I invite you to join other women who started at or above 300 pounds:
http://www.3fatchicks.com/forum/forumdisplay.php?f=124
AND/OR the 100 pound club:
http://www.3fatchicks.com/forum/forumdisplay.php?f=55
There are some inspiring stories there, and lots of support