How can I get a flatter stomach and smaller thighs?

I eat relatively healthy. Almost all I drink is water. I'm somewhat active. I'm a vegetarian so naturally, I eat mostly vegetables and not much chips or anything like that. I believe that my birth control made me a gain a few pounds. I don't need to lose the weight I guess, but I NEED to flatten out my stomach and get smaller legs. Does anyone have any tips/ideas?! I'm particularly looking for something other than sit ups.