Little black dress

I have one month to lose 7 pounds, in my fanny, just so I can fit into my little black bridesmaid dress (that the lady at the store said I didn't need a bigger size) and I need help! Then after that battle I have to try and lose 15 more pounds during the "feeding frenzy" months so that in March I can show up in Vegas with a swimsuit ready body just to lead into another wedding and then back around to the summer. My issue:  I lack motivation. I know what I need to do and how often but when it comes to actually doing it I flake. I need out of this funk! Oh I'm Erin by the way, 28 years old and live in Naperville. I have a membership to all the xsports so if anyone wants a partner let me know. I hate walking into what my roommate and I call "the judgement room" (weight room) alone.