LOL Bridget! your bum is too big compared to what? Folk like big bums as long as the owners of them don't get too wierd about them and start reversing out of rooms. Neither should they refuse to let them be seen naked on the grounds that they may have cellulite. It is a known fact that men are not concentrating on cellulite at this point in an encounter

Seriously, you can't 'spot reduce' just your bum, your overall weight loss will affect that. You can tone it up though. Anything using those big bum muscles will help such as:

hiking up hills
running
skating
cross country skiing
steppers - or running up stairs
leg kick backs (on all fours, bend leg at knee, push foot towards ceiling)
squats

Take care, Jay

PS Jennifer Lopez has a big bum and it doesn't seem to do her any harm