I'm skinny but have a big, low that looks ridiculous, is there any way to perky it up?

I'm really thin, I have a tiny waist and flat chest, but all the weight that I gain goes to my rear end, which wouldn't be so bad if it would just ride up a little higher but it looks saggy! Its not too flabby, just saggy :( I think its in my genetics to have a large un-perky bottom, but would lots and lots of exercise help ?