I reckon I might participate in this challenge with you! Five months sounds like a good amount of time to lose some weight. I want to lose 10, so although its not as much as you want to lose, its going to be tough all the same.
I want to start on Monday (because I'm getting married this weekend and don't want to deny myself all the great things in life on my wedding day, like french bubbles), which will make my starting date Monday August 3 and will make my finish date January 3. This poses a problem, as Christmas is right at the end of my challenge, but I'll try and do my absolute best around the silly season.
My biggest challenge is going to be motivating myself to do more exercise, and not drinking wine. I love a good glass or two of wine in the evening, but I reckon thats a huge reason as to why I've put on all this weight. I also teach aerobics four mornings a week, but my body is so used to the routine and the class that some mornings I hardly break a sweat these days. So I think I need to NOT count those classes in my exercise routine, what do you think?