For me there are a few things that are fueling my current motivation to lose weight.
1 - I'm starting to realize that I can't take health for granted. So far I've been very lucky (knock on wood), but that can't last forever, especially if I'm not trying at all to stay healthy! And getting older (yikes!)
2 - Another big thing for me is to be in better shape to play sports with other people so that I'm not always the weak link - the one that runs out of stamina first. It's starting to irritate me that I'm not able to play as well as I want to or feel that I should be able to. And being top-heavy really screws up my balance for skating or just playing sports that require running!
3 - It would be nice to look better, to feel more confident in certain clothes, bathing suits etc. This is not my top reason at the current moment because I feel that I have a long way to go before I get to what I perceive as a more 'normal' size, but there are some love-handles and then some that I would more than willingly give up to make clothes look just that much better on me!