I really don't know what my problem is......

I can't even keep track of the number of times I have announced "I am starting over!" when it comes to weight loss. Sometimes I will do really well for the first couple of weeks, freshly motivated to take this challenge on. More often then not, though, I never even make it that far. I never get past the "thinking about it" part to the "actively doing something about it" part. I have all these reasons as to why I want to lose the weight, but it seems like nothing really, truly motivates me. If it did, you would think I'd be out there exercising, rather than sitting here at the computer. Even the fact that my boyfriend and I are talking marriage hasn't pushed me to going for my goal. And I know I don't want to walk down the aisle in a size twenty or larger wedding dress. I just can't figure out what it is that is keeping me from getting up off my lazy bum and actually trying. The only reason I can think of, is that deep down somewhere inside I'm scared. Whether it's that I'm scared of how other people will treat me, or if it's that I'm scared I will look too different and my boyfriend will no longer be attracted to me, or what, I don't know. I just really hope I get this figured out soon.