Size reduction...

It seems like this question has been asked somewhere recently, but I can't find it, so I'm just going to ask again. I made an animated icon, and the file size is too big. I tried to just reize the dimensions, but that didn't help much at all. Could someone explain to me which options you can change to reduce an animation file in Animation Shop? It's at about 80 kb right now, and I need to get it down to 40 kb.